2000 Census: Progress Made on Design, but Risks Remain (Letter Report,
07/14/97, GAO/GGD-97-142).

Pursuant to a congressional request, GAO updated the information
provided in its October 25, 1995 testimony on the Census Bureau's plans
for the 2000 Decennial Census, focusing on: (1) the Bureau's progress on
its plans concerning the initiatives discussed in GAO's 1997 testimony;
and (2) whether the Bureau has demonstrated the feasibility of its plans
for carrying out the 2000 Decennial Census.

GAO noted that: (1) since GAO's October 1995 testimony, the Census
Bureau has continued with the planning of the new design initiatives
that GAO and others have suggested, which are aimed at increasing the
mail response rate; (2) this is important because it will reduce the
need for follow-up visits by enumerators, the most costly, difficult to
manage, and error-prone operation in the census; (3) the Bureau has
continued to develop its plan for dealing with those who do not respond
by mail and for checking the quality of the results it gets from mail
responses and from visits by enumerators; (4) its current plan, which
was put forth in March 1997, is to statistically sample those who do not
respond to its mail survey; (5) the Bureau believes that this approach
offers the best combination of reduced costs, improved accuracy expected
at various geographic levels and operational feasibility; (6) the Bureau
developed accuracy estimates by simulating what the results of the
census would likely be under various design options; (7) after the
Bureau made several modifications, GAO concluded that, if the Bureau's
methods and assumptions were properly applied, the final data produced
in June 1997 should be generally reasonable for use in projecting the
likely effects of the Bureau's proposed sampling and statistical
estimation initiatives; (8) because of concerns about the potential
effects of sampling at the local level, GAO requested that the Bureau
provide more detailed data on error rates at the census tract level; (9)
the Bureau's simulations showed that the March 1977 sampling design plan
would likely produce more accurate population estimates in two-thirds of
the census tracts than using a conventional design once again; (10) as
of July 1, 1997, the Bureau had not shared the detailed results of its
analysis with Congress, nor had it yet fully demonstrated the
operational feasibility of its current plan to Congress; (11) the Bureau
is planning a dress rehearsal for the 2000 Census in 1998 to demonstrate
and test its design features; and (12) it is important for Congress and
the administration to reach agreement on the design as soon as possible
before the dress rehearsal so that: (a) the Bureau can test what it
plans to implement in 2000; (b) Congress and the Bureau can discuss the
operational feasibility of the plan in terms of the dress rehearsal
results; and (c) Congress and the Bureau can determine whether the dres*

--------------------------- Indexing Terms -----------------------------

 REPORTNUM:  GGD-97-142
     TITLE:  2000 Census: Progress Made on Design, but Risks Remain
      DATE:  07/14/97
   SUBJECT:  Census
             Data collection
             Population statistics
             Statistical methods
             Projections
             Surveys
             Data integrity
             Interagency relations
             Cost control
             Planning
IDENTIFIER:  2000 Decennial Census
             Census Bureau Post Enumeration Survey
             Census Bureau Outreach and Promotion Initiative
             
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Cover
================================================================ COVER


Report to the Ranking Minority Member, Committee on Governmental
Affairs, U.S.  Senate

July 1997

2000 CENSUS - PROGRESS MADE ON
DESIGN, BUT RISKS REMAIN

GAO/GGD-97-142

2000 Census Design

(410022)


Abbreviations
=============================================================== ABBREV

  CAPI - Computer-assisted personal interviewing
  CV - Coefficient of variation
  DSE - Dual system estimation
  ICM - Integrated coverage measurement
  OMB - Office of Management and Budget
  PES - Post enumeration survey
  SE - Standard error

Letter
=============================================================== LETTER


B-276531

July 14, 1997

The Honorable John Glenn
Ranking Minority Member
Committee on Governmental Affairs
United States Senate

Dear Senator Glenn: 

This letter responds to your request that we update the information
provided in our October 25, 1995, testimony on the Census Bureau's
plans for the 2000 Decennial Census.\1 In that testimony, we
summarized the work we did in reviewing the results of the 1990
Census, which was the most costly in history and which produced data
that were less accurate than those from the 1980 Census, leaving
millions of Americans--especially members of minority
groups--uncounted.  A key reason for the increased cost and decreased
accuracy was a sharp decline in the proportion of households that
returned questionnaires by mail, causing the Bureau to spend hundreds
of millions of dollars to send Bureau employees, known as
enumerators, to try to collect census information directly from
individual citizens.  We and others concluded that the established
approach used for taking the census in 1990 had exhausted its
potential for counting the population cost-effectively and that
fundamental design changes were needed to reduce census costs and
improve the quality of the data collected. 

In that testimony, we also detailed how several of the initiatives
that the Census Bureau was planning for the 2000 Decennial Census
were consistent with suggestions that we had made since the 1990
Census.  These initiatives included (1) simplified and streamlined
census questionnaires, (2) multiple mail contacts to prompt a
response, (3) increased use of the Postal Service to improve the
master address file for the census and identify vacant and
nonexistent housing units, and (4) the use of statistical sampling
and estimation procedures aimed at reducing the cost and increasing
the accuracy of the census. 

However, in that testimony, we also raised concerns that the further
the Census Bureau proceeded with design plans for conducting the 2000
Census without input from Congress, the less Congress would be able
to affect the census design without significant risk of wasted
expenditures and unacceptable results.  In the intervening months,
the administration has been unable to come to agreement with Congress
on critical design and funding decisions.  In February 1997, we
designated the 2000 Decennial Census a new high-risk area because of
the possibility that delays could jeopardize an effective census and
increase the likelihood that billions of dollars could be spent and
the nation still be left with demonstrably inaccurate census
results.\2

The objectives of this report are to (1) provide information on the
progress that the Bureau has made on its plans concerning the
initiatives discussed in our October 1995 testimony and on other
initiatives that the Bureau has promoted since the testimony and (2)
assess whether the Bureau has demonstrated the feasibility of its
plans for carrying out the 2000 Decennial Census. 


--------------------
\1 Decennial Census:  Fundamental Design Decisions Merit
Congressional Attention (GAO/T-GGD-96-37, Oct.  25, 1995). 

\2 The High-Risk Series (GAO/HR-97-2, Feb.  1997) is a special effort
to review and report on the federal program areas we have identified
as high risk because of their vulnerability to waste, fraud, abuse,
or mismanagement. 


   RESULTS IN BRIEF
------------------------------------------------------------ Letter :1

Since our October 1995 testimony, the Census Bureau has continued
with the planning of the new design initiatives that we and others
have suggested, which are aimed at increasing the mail response rate. 
This is important because it will reduce the need for follow-up
visits by census enumerators, the most costly, difficult to manage,
and error-prone operation in the census.  These initiatives include
such changes as redesigning the questionnaires used to collect
information from the public to make them shorter, simpler, and more
user friendly, as well as contacting people by mail more than one
time to encourage responses.  The Bureau believes that its
initiatives in this area will produce a mail response rate of about
67 percent from the nation's housing units, which would be about 2
percent higher than the response rate achieved in 1990 and about 12
percent higher than the 55-percent rate the Bureau would expect to
achieve without the initiatives. 

The Bureau also has continued to develop its plan for dealing with
those who do not respond by mail and for checking the quality of the
results it gets from mail responses and from visits by enumerators. 
Its current plan, which was put forth in March 1997, is to
statistically sample those who do not respond to its mail survey.  It
plans to do this by directly sampling nonrespondents in every census
tract--which is a small geographic area with an average population of
about 4,000 people--in the country until it has information on 90
percent of the housing units in each tract.  It will then use
statistical methods to estimate the data for the remaining 10 percent
of the housing units by projecting the information it obtains from
its nonresponse follow-up sample. 

The Bureau's current plan then calls for staff to be sent to gather
another sample of 750,000 housing units and for these independently
collected data to be compared with the information obtained from the
preceding data collection efforts, such as mail-backs and nonresponse
follow-up.  Again using statistical methods, the Bureau plans to use
the results of its 750,000-household quality check to complete its
final population totals. 

The Bureau believes that this approach offers the best combination of
reduced costs, improved accuracy expected at various geographic
levels, and operational feasibility.  According to the Bureau's cost
estimates, using this plan would save between $700 and $800 million
off the cost of using a conventional census plan that incorporated
all of the new initiatives proposed for the 2000 Census except those
involving sampling and statistical estimation. 

The Bureau developed accuracy estimates by simulating what the
results of the census would likely be under various design options. 
We reviewed the Bureau's simulations and identified several
shortcomings in the methods and assumptions it used for developing
and presenting the accuracy estimates.  After the Bureau made several
modifications, we concluded that, if the Bureau's methods and
assumptions were properly applied, the final data produced in June
1997 should be generally reasonable for use in projecting the likely
effects of the Bureau's proposed sampling and statistical estimation
initiatives.  We recognize that because the actual census environment
and methods in 2000 may vary from those that were simulated and
tested, the Bureau may not actually achieve these results for the
2000 Census.  However, because these types of data are the best
available to reflect the probable effects of an actual census, we
believe it is reasonable to use them to attempt to project the
possible effects of various Bureau design options on the 2000 Census. 

The Bureau's final data showed that, under the Bureau's March 1997
plan for the 2000 Census, the relative error in census data (i.e.,
the measured error in terms of a percentage of the area's population)
would likely be about 0.1 percent for the national total and an
average of 0.5 percent for states, 0.6 percent for congressional
districts, and 1.1 percent for census tracts.  The Bureau's
simulations projected that a design that did not use sampling for
nonresponse follow-up and a quality check would likely result in
relative error rates of about 1.9 percent for the national total and
average error rates of 1.9 percent for states, congressional
districts, and census tracts. 

Because of concerns about the potential effects of sampling at the
local level, we requested that the Bureau provide more detailed data
on error rates at the census tract level.  The Bureau's simulations
showed that the March sampling design plan would likely produce more
accurate population estimates in two-thirds of the census tracts than
using a conventional design once again.  However, one third of the
tracts would likely have less accurate estimates when compared to the
conventional design. 

As of July 1, 1997, the Bureau had not shared the detailed results of
its analysis with Congress, nor had it yet fully demonstrated the
operational feasibility of its current plan to Congress.  Although
the Bureau has revised its plan for the 2000 Census several times
since the October 1995 testimony, it provided only limited details to
demonstrate and allow those outside the Bureau to check and
scrutinize the relative merits of the various alternatives. 

Citing, in part, the lack of sufficient data on the effects of the
Bureau's proposed use of sampling and statistical estimation methods,
some Members of Congress have expressed concern about the Bureau's
plan.  They also questioned the use of sampling and statistical
estimation on constitutional and statutory grounds.  While a draft of
this report was with the Bureau for comment, Congress enacted
legislation (Public Law 105-18) requiring the Department of Commerce
to provide detailed data about the Bureau's plan by July 12, 1997. 
It is unlikely that Congress and the administration will come to an
agreement on the design and its associated funding level for the 2000
Census without continuous, full, and open disclosure of the effects
of its plan at all levels of geography.  Thus, the Bureau needs to
continue to keep Congress informed of any changes in its approach to
the census or refinements to its data that it makes after July 12,
1997. 

The Bureau is planning a dress rehearsal for the 2000 Census in 1998
to demonstrate and test its design features.  It is important for
Congress and the administration to reach agreement on the design as
soon as possible before the dress rehearsal so that (1) the Bureau
can test what it plans to implement in 2000, (2) Congress and the
Bureau can discuss the operational feasibility of the plan in terms
of the dress rehearsal results, and (3) Congress and the Bureau can
determine whether the dress rehearsal outcomes are sufficiently
similar to the results of the Bureau's research and simulations to
proceed with that design for the census.  Time and resources could be
wasted if the Bureau tests a plan in 1998 that Congress later finds
it cannot accept. 


   BACKGROUND
------------------------------------------------------------ Letter :2

The decennial census is the nation's most comprehensive and expensive
statistical data-gathering program.  The Constitution requires a
decennial census of the population in order to reapportion seats in
the House of Representatives.  Public and private decisionmakers also
use census data on population counts and social and economic
characteristics for a variety of purposes.  State and local
redistricting; allocations of government funding; and many planning
and evaluation activities, such as site selection for new schools,
market research, and evaluations of local labor markets, rely on
decennial census data.  In addition, the census is the only national
source of detailed population statistics for small geographic areas,
such as towns or school districts, and for population groups, such as
Native Americans. 

The Bureau has used short- and long-form questionnaires to carry out
the decennial census.  Most households are sent a short form to
complete; however, some are asked to complete the long-form
questionnaire.  In 1990, for example, about one in six households was
required to complete a long-form questionnaire.  Many federal
agencies use information collected through the decennial census
long-form questionnaire as a source of data for their own statistical
and programmatic activities. 

Since 1970, the Bureau has used essentially the same methodology to
count the vast majority of the population during the decennial
census.  It develops an address list of the nation's housing units
and mails census forms to those housing units that ask the occupants
to mail back the completed forms.  The Bureau then hires temporary
census-takers, known as enumerators, by the hundreds of thousands to
gather the requested information for each nonresponding housing unit. 

A critical factor affecting the cost of a census is the necessity for
the Bureau to follow up on nonresponding housing units.  A declining
response rate to the census questionnaires has increased the Bureau's
costly nonresponse workload.  In the 1980 Census, the mail response
rate was 75 percent, 3 percentage points lower than it was in the
1970 Census.  In the 1990 Census, the response rate dropped to 65
percent, 10 percentage points lower than it was in 1980.  According
to Bureau officials, if the downward trend in public cooperation
continues without changes to the Bureau's methods for soliciting
responses, the mail response rate could be as low as 55 percent in
2000 and generate a potential nonresponse workload of about 53
million cases, a substantial increase over the 1990 nonresponse
workload of about 34 million cases. 

Since 1970, census costs have been increasing faster than inflation,
even after allowing for population growth.  In 1990 constant dollars,
total census cycle costs were $0.7 billion in 1970, $1.8 billion in
1980, and $2.6 billion in 1990.\3 Furthermore, the cost per housing
unit jumped from $11 in 1970, to $20 in 1980, and to $25 in 1990. 
The Bureau estimated that, if census-taking methods were not changed,
the 2000 Census could cost almost $5 billion (in 2000 dollars). 

Unfortunately, the nation's growing investment in the census has not
resulted in uniformly more accurate results.  Since the Bureau began
evaluating census coverage in 1940, it has documented a net
undercount, which is the difference between the estimated population
and the census count.  Figure 1 shows the net undercount for each
census since 1940; note that the undercount decreased for each
subsequent census until it increased for the 1990 Census. 

   Figure 1:  The Net Undercount
   Since 1940

   (See figure in printed
   edition.)

Source:  Bureau of the Census estimates of net undercounts based on
demographic analysis and derived largely from administrative data,
such as birth and death records, as of June 1991. 

The net undercount masks an even larger gross error in the census. 
The 1990 Post Enumeration Survey (PES) provided a greater level of
detail on such errors than is possible using demographic analysis.\4
While the net undercount, as measured by the PES, was about 1.6
percent of the population (about 4 million persons) in 1990, this
does not mean that over 98 percent of the population was accurately
counted, as is often reported.  In fact, the number of persons missed
in the 1990 Census was partially offset by millions of persons who
were improperly included.  The Bureau estimated that about 6 million
persons were counted twice in the 1990 Census, while 10 million were
missed.  The sum of these numbers--16 million--represents a minimum
tally of gross errors since they do not include other errors, such as
persons assigned to the wrong locations. 

Even more troubling, the Census Bureau's evaluations showed a
persistent differential undercount of minority groups.  The decennial
census has not counted all population groups and areas in the United
States equally well.  The 4.4 percentage point difference in the 1990
net undercount between blacks (5.7 percent) and nonblacks (1.3
percent) was the highest since the Bureau began estimating coverage
in the 1940 Census. 

After the 1990 Census, we, Congress, the Department of Commerce and
its Office of the Inspector General, the Bureau itself, and other
stakeholders, such as advisory committees to the Bureau, all
recognized the need to reassess the conventional census-taking
approach to ensure the achievement of a more accurate and
cost-effective census in 2000.  The Bureau evaluated the results of
the 1990 Census to develop new, cost-saving approaches that could
improve accuracy for the next census.  For example, the single most
expensive component of the census was the operation to gather data on
nonrespondents, which took 14 weeks, rather than the 6 weeks
originally scheduled.  The final 6 weeks were devoted just to
resolving the last 10 percent of the nonresponse cases.  Furthermore,
evaluations demonstrated that the amount of error in the census
increased precipitously as time and effort were extended to count the
last few percentages of the population, with the Bureau ultimately
accepting whatever information could be obtained using "last resort"
or "closeout" procedures, such as interviews with neighbors, mail
carriers, or other persons who were not residents of the nonresponse
households.  The National Academy of Sciences also reexamined the
conventional census design and proposed alternatives for 2000.  The
general conclusion from these extensive efforts was that fundamental
changes were needed in the census design to accurately and
economically account for the U.S.  population in the next census. 


--------------------
\3 Constant-dollar value is measured in terms of prices for a base
period, to remove the influence of inflation.  The resulting
constant-dollar value is the value that would exist if prices had
remained the same as in the base period. 

\4 The 1990 PES was designed to estimate the net undercount in the
census.  It was a matching study in which the Bureau interviewed a
sample of households several months after the census.  The results of
these interviews were compared with census questionnaires to
determine whether each person was correctly counted in the census,
missed, or included in error. 


   SCOPE AND METHODOLOGY
------------------------------------------------------------ Letter :3

To provide information on the progress that the Bureau has made on
its plans concerning the initiatives discussed in our October 1995
testimony and on other initiatives that the Bureau has proposed since
the testimony and to assess the feasibility of the Bureau's plans for
carrying out the 2000 Decennial Census, we (1) reviewed Bureau
research, evaluation, and planning documents and data produced since
our October 1995 testimony; (2) interviewed Bureau, Department of
Commerce, and Office of Management and Budget (OMB) officials; and
(3) reviewed a September 1996 report of the House Committee on
Government Reform and Oversight entitled Sampling and Statistical
Adjustment in the Decennial Census:  Fundamental Flaws, our work on
prior decennial census activities, and various reports prepared by
the National Academy of Sciences related to planning for the 2000
Census.  This report provides a summary of our work and its results. 
It includes a technical appendix (app.  I) that explains in more
detail the Bureau's sampling and statistical estimation initiatives
and our analysis of their effects.  It also includes an appendix
(app.  II) presenting the Bureau's most recent summary information
and explanation of projected differences in the costs and accuracy of
selected census designs. 

In assessing the Bureau's plans for its statistical sampling and
estimation initiatives, we began with the data and research that the
Bureau provided, mostly from simulations that the Bureau performed
using 1990 Census data and results from the 1995 Census Test. 
Because it was impractical for us to verify the underlying census
data the Bureau used, we accepted the census data in the Bureau's
analysis without further verification.  However, we challenged the
Bureau's analysis in several respects, including the methods and
assumptions for producing the data and the way they were presented. 
In response to our questions, the Bureau made several modifications,
most of which were to clarify the data and assumptions.  Furthermore,
to produce the final data comparing the design alternatives included
in appendix II, the Bureau redid the simulations after detecting
shortcomings in the draft data.  To ensure its accuracy, the Bureau
had two groups working independently on the simulations and
reconciled differences prior to providing the final data to us. 
Because the actual census environment and methods in 2000 may vary
from those that were simulated and tested, the Bureau may not
actually achieve these results for the 2000 Census.  However, because
these types of data are the best available to reflect the probable
effects of an actual census, we believe it is reasonable to use them
to attempt to project the possible effects of various Bureau design
options on the 2000 Census. 

It is important to note that the Bureau, which will continue its
research efforts until the 2000 Census begins, is still refining,
modifying, and testing elements of its proposed census design.  For
example, the Bureau was in the process of revising and verifying its
cost estimates when we completed our work.  Therefore, we relied on
the most recent available cost data, those from June 1997, in the
final version of this report, but the Bureau's estimates are still
subject to revision.  Finally, because all initiatives of the
Bureau's current plan for the 2000 Census are closely related, none
of the initiatives should be considered in isolation from the rest of
the census design. 

We did our work in Washington, D.C., and at the Bureau's headquarters
in Suitland, MD, between October 1995 and June 1997 in accordance
with generally accepted government auditing standards.  We requested
comments on a draft of this report from the Secretary of Commerce. 
We received comments from the Director of the Bureau of the Census
(see app.  III), which we address at the end of this letter. 


   OBTAINING RESPONSES TO CENSUS
   QUESTIONNAIRES PRESENTS A
   FORMIDABLE CHALLENGE
------------------------------------------------------------ Letter :4

Declining rates of public response to census questionnaires have
generated a costly, time-consuming workload for the Bureau.  The key
to a successful census as measured in terms of cost and data quality
is obtaining mail responses to census questionnaires from residents
of housing units.  The 65-percent mail response rate for the 1990
Census was troublesome to the Bureau because of the extensive
follow-up effort required to obtain information from nonresponding
housing units.  In our October 1995 testimony, we reported the status
of new Bureau initiatives that were aimed at obtaining responses to
census questionnaires.  These initiatives included the creation of
simplified and streamlined census questionnaires and the use of
multiple mail contacts to prompt a response.  Subsequently, the
Bureau announced the development of a new outreach and promotion
program to encourage public cooperation.  The Bureau expects that,
when combined, these initiatives should produce a mail response rate
of 66.9 percent.  This is lower than the 70-percent response rate
that the Bureau expected to receive in the 1990 Census and only
slightly higher than the 65-percent response rate achieved in 1990. 
However, it is 12 percentage points higher than the Bureau expects to
achieve without the initiatives.  Bureau officials did not quantify
the individual effect of these initiatives, stating that their
effects were too interrelated to be measured separately. 


      SIMPLIFIED AND STREAMLINED
      QUESTIONNAIRE HAS POTENTIAL
      TO IMPROVE MAIL RESPONSE
      RATES
---------------------------------------------------------- Letter :4.1

Since the 1990 Census, the Bureau has been working to simplify and
streamline the short-form questionnaire.  As of February 1997, the
draft short-form questionnaire that the Bureau plans to use for the
2000 Decennial Census contained eight questions, which is six
questions fewer than were on the form used in 1990.  The new
short-form questionnaire now asks only for the name, age, gender,
race, ethnicity, relationship of each household member, and housing
tenure (owned or rented).  Over the years, we have strongly suggested
such an abbreviated form.  The Bureau also has been simplifying the
long-form questionnaire that asks for more detailed sociodemographic,
economic, and housing information.  As in the 1990 Census, the Bureau
plans to ask one in six housing units to complete a long form. 
Although the final design is still being evaluated, the Bureau
expects the 2000 Census long-form questionnaire to have fewer
questions than the 1990 Census long-form questionnaire had. 

The 1995 Census Test evaluated one short-form and several long-form
questionnaires of different lengths.  The long-form questionnaires
ranged in length from 16 to 53 questions, with even the longest
version including 11 fewer questions than did the 1990 long-form
questionnaire.  The 1995 Census Test showed that, the shorter the
questionnaire, the more likely housing units were to respond.  During
the test, the response rate for short-form questionnaires was 55
percent, whereas the response rate for the three versions of the long
form ranged from 38.1 percent to 46.8 percent, with the longest
questionnaire having the lowest response rate. 

During 1996, the Bureau conducted the 2000 Census Test to help it
determine which specific question wording, formatting, and sequencing
would elicit the most accurate responses.  It also tested
alternative-form designs and assessed the differences in coverage,
completeness, and cooperation.  As part of this test, short-form
questionnaires were sent to 42,000 housing units, and various
versions of the long form were sent to 52,500 housing units.  The
Bureau released preliminary test results in December 1996 that
indicated no statistical difference in the housing units'
responsiveness to the various lengths of either the short-form or
long-form questionnaires.  However, the long-form questionnaire had a
lower average response rate (65 percent) than did the short-form
questionnaire (72 percent). 

The Bureau is continuing to work on the design of the census
questionnaires with the assistance of marketing and survey design
consultants, giving consideration to the printing, mailing, and
processing of a large volume of questionnaires.  Bureau officials
told us that several visual design issues, such as illustrations on
the census form that are aimed at promoting response, are still to be
resolved. 

As reported in our 1995 testimony, although the Bureau continues to
progress in simplifying the census questionnaires, it has not gained
consensus among policymakers and other stakeholders on the content of
the questionnaires, their ultimate length, or the use of a long form. 
Although some Members of Congress have raised questions about the
length of the short-form questionnaire and the need for the long-form
questionnaire, the Bureau plans to use both the short- and long-form
questionnaires unless formally directed not to do so by Congress.  In
the meantime, demands on the Bureau for data collection are
increasing.  For example, during 1996, the Welfare Reform Act was
enacted, which, among other things, mandates that the Census Bureau
collect data on grandparents as primary caregivers for their
grandchildren.  The Bureau is currently proposing to add two
questions to the long-form questionnaire to comply with the act. 


      MULTIPLE MAIL CONTACTS
      SHOULD PROMOTE INCREASED
      RESPONSE TO QUESTIONNAIRES
---------------------------------------------------------- Letter :4.2

We first suggested the use of a multiple mail contact strategy after
we analyzed the results of the 1980 Census.  The Bureau's initiative
for multiple mail contacts consisted of four household contacts--a
pre-notice letter, an initial questionnaire, a thank you/reminder
card, and a replacement questionnaire.  Bureau evaluations during
1995 showed that multiple mail contacts should increase mail response
rates.  Precise percentages could not be determined, however, because
Bureau officials could not determine which part of the multiple mail
contact initiative prompted the response.  For example, some housing
units may have returned the original census questionnaire because
they received a thank you/reminder card, while others may have
returned the questionnaire without receiving the cards.  The Bureau's
test of its initiative was not designed to permit an analysis of this
nature. 

Nevertheless, during testing in 1995, about 7 percent of housing
units responded to the questionnaires using the replacement
questionnaires, indicating that multiple mail contacts prompted
responses.  Considering that follow-up on each 1 percent of
nonresponding housing units is expected to cost about $25 million,
increasing the response rate through multiple mail contact could
produce significant savings.  Furthermore, because of the
approximately 97.3 million housing units for which census
questionnaires are projected to be mailed in 2000 and returned by
mail, the cost of multiple mail contacts could be a significant but
worthwhile investment since it may free the Bureau from having to do
follow-up visits to approximately 6.8 million housing units. 

According to Bureau officials, only a limited number of
printing/mailing vendors who are technically qualified have shown
interest in bidding on the Bureau's 2000 Decennial Census
questionnaire printing contract.  Because of the large volume of
printing/mailing involved and the remailing time constraints, most of
these interested printing vendors did not believe that a replacement
questionnaire could be implemented under the Bureau's requirements. 
Therefore, the Bureau changed its initiative to include sending all
housing units a replacement questionnaire, although it plans to
continue discussing less costly and less duplicative methods with
vendors for possible use in the 2000 Census.  Bureau officials, with
assistance from the Government Printing Office, plan to resolve all
questionnaire printing and operational issues and award a printing
contract to a single contractor or a consortium of printing
contractors by December 1998. 


      INCREASED USE OF THE POSTAL
      SERVICE PROVIDES OPPORTUNITY
      FOR SAVINGS
---------------------------------------------------------- Letter :4.3

As we testified in October 1995, the Bureau is working with the
Postal Service and local communities to maintain and update its
address list.  Furthermore, the Bureau is planning to use the Postal
Service to identify vacant and nonexistent housing units early in the
census-taking process to improve data quality and reduce costly
nonresponse follow-up.  Through greater reliance on the Postal
Service and local communities in updating its address list, the
Bureau estimated that it could save as much as $188 million in the
2000 Census.  The Bureau also estimated that the use of the Postal
Service to identify vacant and nonexistent housing units could reduce
nonresponse workload by about 6 percent in the 2000 Census and
thereby save an additional $135 million.  The Census Bureau has
tested and evaluated the use of a combined Census Bureau and Postal
Service master address file and is now in the process of updating the
file for 2000. 

As we stated in 1995, a geographically structured address list is
critical for planning the 2000 Decennial Census because such a list
will enable enumerators to physically locate the addresses of housing
units and determine where they may be missing housing units.  As of
May 1997, the Bureau had updated 85 percent, or 84 million, of the
currently known universe of about 99 million city-style addresses on
its mapping system.\5 Rural addresses, which the Bureau projected
will number about 21.3 million in 2000, are to be identified as they
were in past censuses--by having Bureau employees canvass rural areas
to determine addresses for and geographically locate housing units. 
Postal Service information is not designed to geographically locate
these housing units. 

The Bureau continues to keep pace with its planned schedule for
updating addresses and has determined that March 1999 will be
critical for completing the address list.  At that time, local
governments are expected to review the list and provide updated
information as the Bureau prepares for mailing census questionnaires
in spring 2000.  According to Bureau officials, a special effort will
be needed because the last 10 to 20 percent of the addresses will be
the most difficult for the Bureau to identify because of poor quality
reference sources.  For example, an address zoned for single-family
residents may have been converted to contain two or more households. 


--------------------
\5 Not all of these city-style addresses will be delivered census
questionnaires by the Postal Service; some questionnaires will be
hand-delivered by enumerators and returned through the mail by
respondents. 


      OUTREACH AND PROMOTION
      PROGRAM COULD ENCOURAGE
      PUBLIC RESPONSE TO CENSUS,
      BUT TO WHAT EXTENT IS
      UNCLEAR
---------------------------------------------------------- Letter :4.4

In February 1996, the Bureau unveiled its plans for a new outreach
and promotion initiative, which is expected to cost about $230
million, for encouraging public response to the census.  While not
discussed in our October 1995 testimony, this initiative goes hand in
hand with other initiatives discussed in this report because of its
potential impact on the response rate to, and the cost of, the
census.  One key feature of the outreach and promotion initiative is
cooperative ventures with local governments aimed at involving
elected local officials, business leaders, minority groups, religious
organizations, and others in developing outreach activities within
local communities.  The Bureau's 1995 Census Test indicated that
cooperative ventures with local governments provided a way to promote
public participation in the census.  However, even though local
communities were enthusiastic about participating in the Bureau's
outreach efforts, funding was an issue.  Local governments in urban
areas where response rates are lowest reported that their lack of
funding to promote the Bureau's initiative is an issue.  As was the
case in the 1990 Census, the Bureau's plans do not include funding
for these cooperative ventures, and therefore the level of local
government involvement in the 2000 Census is unclear. 

Another feature of the Bureau's outreach and promotion initiative is
the targeting of certain populations and geographic areas that
historically have been undercounted, such as inner-city populations. 
Several of these targeted methods include the use of community-based
outreach organizations and the use of unaddressed questionnaires that
will not be sent to housing units but rather will be made available
at locations throughout a community, such as in community centers and
convenience stores.  The 1995 Census Test evaluations of targeted
methods showed that the use of community-based organizations provides
valuable assistance to outreach and promotion efforts in
hard-to-enumerate areas.  As a result of the test evaluation, the
Bureau concluded that the use of unaddressed questionnaires increased
response rates by a small percentage, especially from those who may
not otherwise have completed a questionnaire. 

The third feature of the outreach and promotion initiative is the
Bureau's plan to contract with a private-sector advertising firm to
promote the 2000 Census.  The Bureau estimates that this paid
advertising contract will cost about $100 million of the $230 million
budgeted for the outreach and promotion program.  This paid
advertising program will end a 50-year partnership between the Bureau
and the Advertising Council, which provided pro bono promotional
services valued at $65 million for the 1990 Census.\6

By using paid advertising, Bureau officials said that they expect to
have more control over the placement of advertising to reach targeted
populations.  For example, under pro bono promotional services, the
Bureau had no control over the time of day that advertising was
aired.  In contrast, under a paid advertising program, the Bureau can
decide when advertising "spots" should be aired, including during
"prime time" and popular television programs.  The Bureau is still in
the research and development phase of its paid advertising campaign
and plans to spend $450,000 in fiscal year 1997 for focus groups to
develop a census message and image acceptable to the majority of the
population, as well as specific targeted population groups.  The
Bureau plans to incorporate the results of these focus groups into
the final contract for the advertising firm that is selected to carry
out the overall 2000 Census promotional campaign.  The Bureau plans
to award the advertising contract in September 1997.  If funding
permits, Bureau officials said they plan to evaluate their
full-treatment advertising campaign in the 1998 dress rehearsal. 

Although Bureau officials acknowledged that a direct link between
investment in advertising and a corresponding increase in mail
response rates cannot be proven, these officials said that they
intuitively believe that advertising aids response by making people
aware of the census.  Nevertheless, the Bureau's own research found
that, although about 93 percent of the public was aware of the 1990
Census, the mail response rate was only 65 percent.  In a related
example of civic response, although most U.S.  citizens were aware of
the 1996 presidential election, and despite massive advertising by
candidates and political parties, as well as through public service
announcements, only 49.7 percent of the voting age population
exercised their right to vote. 

Although the Bureau expects the use of outreach and promotion to
encourage participation, especially in the hard-to-enumerate areas,
we are concerned that the Bureau's funding plans may not bring the
high response rates hoped for because of other, larger demographic,
economic, and attitudinal variables in our society that cannot be
easily overcome.  For example, in the 1990 Census, the Bureau planned
for a 70-percent mail response rate but achieved only a 65-percent
rate. 


--------------------
\6 The Advertising Council, Inc., is a nonprofit organization
responsible for administering public service advertising campaigns
for television, radio, and print media. 


   THE POTENTIAL EFFECTS OF
   STATISTICAL SAMPLING AND
   ESTIMATION ON CENSUS ACCURACY
   AND COST
------------------------------------------------------------ Letter :5

The Bureau intends to expand the use of statistical sampling and
estimation procedures in the 2000 Decennial Census to reduce the time
and cost required to follow up on housing units that do not respond
to census questionnaires and to improve the accuracy of the
population count through the use of integrated coverage measurement
(ICM) procedures.  ICM is a statistical procedure that is designed to
improve the accuracy of the census count by reconciling the original
census counts with data obtained from an independent sample of
housing units and using the results to adjust the census.  While the
Bureau used sampling and statistical estimation procedures in past
censuses, its current plan for the 2000 Census would greatly expand
reliance on such procedures in producing the final census totals. 

In 1992, after comprehensively studying the 1990 Census, we
recommended that the Bureau consider using statistical sampling to
develop information on nonrespondents in an effort to achieve
significant cost-savings.\7 In our October 1995 testimony, we again
noted that sampling could both improve the accuracy of census data on
nonrespondents and save money.\8 However, we also testified that the
Bureau must be prepared to provide policymakers with data on the
trade-offs between the accuracy and potential cost-savings of
sampling.  In addition, we noted that, if the Bureau were to use
sampling and statistical estimation procedures in the form of ICM to
adjust for undercounting, such procedures must be reliable.  We were
concerned that errors introduced by sampling nonrespondents and using
ICM would overshadow the benefits that these procedures could provide
when applied to smaller geographic levels, such as census tracts.\9

In December 1996, the Bureau began providing us with draft results of
its research using 1990 Census data that were applied to different
design options, and these results were finalized by June 1997.  The
Bureau did not release all of these results publicly.  The results
showed that the Bureau's plan for statistical sampling and
estimation, if effectively implemented, has the potential for
producing a more accurate and less costly census than if only
conventional census procedures were used.  The following sections
summarize the Bureau's general development of sampling for
nonresponse follow-up and ICM since our 1995 testimony and provide a
view of the projected combined effects of these initiatives to
produce the census count.  A fuller and more technical description of
the purpose, strategies, and research on the Bureau's alternative
designs for sampling for nonresponse follow-up and ICM is included in
appendix I. 


--------------------
\7 Decennial Census:  1990 Results Show Need for Fundamental Reform
(GAO/GGD-92-94, June 9, 1992). 

\8 GAO/GGD-T-96-37, October 25, 1995. 

\9 A census tract is a small, relatively permanent statistical
subdivision of a county.  Census tracts usually have between 2,500
and 8,000 persons--averaging about 4,000--and, when first delineated,
are designed to be homogeneous with respect to population
characteristics, economic status, and living conditions.  Census
tracts do not cross county boundaries. 


      SAMPLING FOR NONRESPONSE
      FOLLOW-UP COULD REDUCE COST
      AND SAVE TIME
---------------------------------------------------------- Letter :5.1

Declining rates of public response to the census questionnaires have
generated a costly, time-consuming nonresponse follow-up workload for
the Bureau.  The Bureau had to follow up on about 34 million
nonresponding housing units in 1990.  Although the Bureau plans many
initiatives for the 2000 Census to encourage higher mail response
rates and reduce its reliance on expensive enumerator visits to every
nonresponding housing unit, the nonresponse workload is still
expected to be greater than it was in 1990.  Therefore, after trying
to directly contact every housing unit by providing a census form and
requesting a response, the Bureau plans to sample a portion of the
nonresponding housing units, rather than continuing with 100-percent
follow-up as it did in 1990.  The primary purposes of using sampling
for nonresponse follow-up are to reduce the cost and time required to
finish the census operation.  In June 1997, the Bureau estimated that
its current plan for sampling nonresponding housing units in 2000
could save about $400 million off the cost of using a census design
that incorporated all other improvements on the 1990 model except for
sampling for nonresponse.  Research results also indicated that
sampling can help the Bureau to complete nonresponse follow-up
operations in a much more timely manner than was the case in past
censuses. 

Since our October 1995 testimony, the Bureau has twice revised its
plan for sampling a portion of the housing units that do not mail
back a completed census questionnaire.  Under its original plan,
which was officially presented to the public in February 1996, the
Bureau intended to continue conventional mail response data
collection and follow-up interviews until information was obtained
for 90 percent of the housing units in each county.  The Bureau then
planned to truncate, or stop, conventional follow-up, select a sample
of 1 in 10 of the remaining housing units to interview, and rely on
information obtained from interviewing the sample housing units to
produce census data that would be substituted for all of the
remaining nonrespondents. 

After this plan was announced, some Members of Congress and other
stakeholders and observers raised concerns about the effect of
county-level truncation on the accuracy and fairness (equity) of
census data.  One of the concerns regarding county-level truncation
was that the 90-percent threshold would be achieved primarily by more
complete enumeration of the areas and population groups within a
county that were easiest to count, leaving hard-to-count areas and
subgroups of the population, especially minorities, to be
disproportionately covered by sampling.  In response, the Bureau
decided, in September 1996, that its preferred design would be to
base sampling for nonresponse on mail response rates at the census
tract level while maintaining the goal of obtaining responses from at
least 90 percent of all housing units before relying on sample data
to account for the remaining units.  This change should improve
overall accuracy and fairness because tracts are generally smaller
and more homogeneous than counties.  However, tract-level truncation
will pose some additional challenges in the management and
implementation of census field operations, not the least of which is
the difficulty of tracking and controlling operations for over 60,000
separate tracts instead of for about 3,000 counties. 

The Bureau studied the following three options to determine how best
to implement its revised plan:  (1) truncation at 90 percent, (2)
time truncation, and (3) direct sampling.  Truncation at 90 percent
featured the same basic design as the original February 1996 plan,
except that completion rates would be tracked for each census tract
rather than for each county.  Under this option, the Bureau would
continue conventional follow-up interviews until it had achieved the
90-percent completion threshold for each tract and would then begin
sampling to account for the remaining nonrespondents.  Under the time
truncation option, conventional follow-up interviews would continue
for a predetermined length of time, such as 3 weeks.  After this
initial follow-up period, the Bureau would select a sample of the
remaining housing units in each tract that included enough housing
units to raise the completion rate to at least 90 percent.  For
example, in a tract for which the Bureau achieved a 70-percent
completion rate after this initial follow-up period, two of every
three of the remaining housing units would be selected for the
follow-up sample.  Under the direct sampling option, there would be
no conventional follow-up phase.  Instead, at the end of the mail
response phase, the Bureau would select a sample of the remaining
nonresponding housing units in each tract that would be sufficient to
reach at least a 90-percent completion rate and would then project
the remaining 10 percent.  For example, in a tract with a mail
response rate of 30 percent, six of every seven of the remaining
housing units would be sampled.  Under each of the 3 options, the
Bureau would take a 1-in-10 sample of the remaining housing units for
any tract with an initial response rate of more than 90 percent. 

The Bureau's research indicated that all three options had the
potential to (1) produce results with similar accuracy; (2) reduce
the cost of follow-up operations at least somewhat when compared to
the cost of 100-percent follow-up; and perhaps most important, (3)
allow the Bureau to complete nonresponse operations in time to also
implement and complete ICM.  Of the three nonresponse sampling
options the Bureau considered, direct sampling appeared to produce
the greatest benefits in terms of cost, accuracy, and operational
feasibility.  Therefore, in March 1997, the Bureau selected the
direct sampling design option.  The Bureau estimated the cost of
implementing direct sampling to be about $200 million less than
truncating at 90 percent and $600 million less than using the time
truncation option.  In simulations of the accuracy of different
options, direct sampling produced slightly better results,
particularly for small geographic areas, such as census tracts.  This
option was also favored by Bureau field staff because it is simpler
to implement.  However, direct sampling differs the most from the
plan the Bureau originally proposed and would mean that nonresponding
housing units that were not selected as part of the sample would not
have another chance to be interviewed by census enumerators.  This
option, therefore, may be somewhat more difficult for the public to
understand and accept. 


      ICM COULD IMPROVE THE
      ACCURACY OF THE POPULATION
      TOTALS
---------------------------------------------------------- Letter :5.2

The purpose of ICM is to reduce coverage error in the census,
particularly the differential undercount of minorities and other
hard-to-enumerate populations and areas.  Even if all other redesign
initiatives produce the anticipated improvements in the conventional
census counting operations, the evidence from past census evaluations
indicates that coverage errors and differential net undercounts in
the census data will still occur.  Evaluations have demonstrated that
the census misses entire housing units (and any occupants), misses
people within housing units that it does count, and includes other
persons in the census counts in error (e.g., counting them more than
once or in the wrong place).  Young adult males, members of ethnic
and racial minorities, renters, and people living in rural areas,
among others, are more likely than other categories of residents to
be undercounted by the census.  Evaluations of the 1990 Census also
showed that error rates were significantly higher for persons living
in housing units enumerated using "last resort" or "closeout"
procedures at the end of nonresponse follow-up operations, when the
Bureau accepted information from persons who were not residents of
the households. 

ICM is designed to use the results of a coverage measurement survey
to do a quality check in which enumerators visit an independent
sample of households to check the accuracy of the original census
data.  ICM would be conducted after basic data collection, including
nonresponse follow-up, had ended and would estimate the extent to
which people were correctly counted, missed, or included in error by
the census.  These estimates would then be used to correct coverage
errors in the results of previous data collection efforts.  This
would be the last phase in completing the census and producing the
final census results.  Although the Bureau has used coverage
measurement surveys since 1950 to help it determine the magnitude and
characteristics of census errors and undercounts, it has not used the
findings of these evaluations to correct for coverage errors in the
decennial census data tabulations.\10 A key feature of the Bureau's
current plan for 2000 is to produce a one-number census by
integrating an adjustment into the basic process for developing
decennial census data tabulations. 

The Bureau designed the proposed ICM for 2000 to address several
major weaknesses of the coverage measurement survey that was used in
the 1990 Census (the PES), especially those regarding timeliness and
the accuracy of estimates for subnational geographic areas.  In the
1995 Census Test, new procedures and reliance on improved survey
technology demonstrated the potential to improve the timeliness of a
post-census quality check.  The Bureau was able to produce the final
test census results before the end of 1995, a significant improvement
over the performance of the 1990 PES, which did not generate adjusted
census estimates until the spring of 1991, well after the December
31, 1990, deadline for apportionment totals.  The Bureau also plans
to use a sample in 2000 that is approximately 5 times larger than the
1990 PES sample (about 750,000 housing units versus about 150,000). 
This larger sample is designed to allow the Bureau to produce direct
estimates for each state and improve the quality of estimates for
smaller geographic areas.\11

While results from research and testing to date have been promising
in general, it is also clear that the Bureau's plans for further
research and testing are important to the development of ICM for the
2000 Census.  The Bureau experienced some operational and technical
problems with ICM in the 1995 Census Test.  For example, enumerators
tested the use of laptop computers to quickly reconcile the
information obtained during the ICM visit with original census data
but found that the data were not always contained in the computer,
making on-the-spot reconciliations impossible. 

The Bureau is currently testing and evaluating redesigned procedures
and its survey instrument.  The ICM survey portion of this test began
in January 1997, and the results of the test should help determine
whether ICM operational and technical problems have been addressed
sufficiently.  However, evaluations from this test are not expected
to be completed until fall 1997, and Bureau officials have indicated
that evaluation of ICM may continue through the Census 2000 Dress
Rehearsal. 


--------------------
\10 The Bureau has used the 1990 Census adjustment factors for
purposes of adjusting its survey controls but not the decennial
census tabulations. 

\11 A direct estimate is based entirely on data from the area for
which the estimate is calculated.  For instance, a direct population
estimate for Missouri would be calculated using only data collected
from Missouri.  Indirect estimates, such as the 1990 PES state
population estimates, draw on data from outside the area being
estimated. 


      COMBINED EFFECTS OF PLANNED
      SAMPLING FOR NONRESPONSE
      FOLLOW-UP AND ICM ON
      POPULATION TOTALS
---------------------------------------------------------- Letter :5.3

The effects of the proposed sampling for nonresponse follow-up and of
ICM procedures on the success of census operations and the quality of
the resulting data need to be viewed in combination to be meaningful. 
Sampling a portion of the nonresponse workload can save time and
money when compared with the option of 100-percent follow-up of
nonrespondents; however, it is unlikely to significantly change
(either improve or decrease) census accuracy.  Conversely, ICM, which
would increase costs, is designed to address problems with census
accuracy.  But ICM is unlikely to be successful unless preceding data
collection efforts, in particular nonresponse follow-up, are
completed on schedule.  ICM is designed to reduce the systematic bias
observed in past censuses (i.e., differential undercounts), but it
also introduces sampling error.  Similarly, a census design that
would not include sampling for nonresponse follow-up or ICM would
also involve trade-offs.  For example, such designs would be easier
to explain to the public, would more closely resemble past censuses,
and would not introduce the level of uncertainty in the results that
accompanies sampling.  However, these designs are also likely to be
more expensive and have shown no likelihood of reversing or
significantly reducing past accuracy problems in census data. 

The Bureau shared with us data and analysis it had developed from its
research and simulations done for the different design alternatives
it considered for the 2000 Census.  We reviewed the Bureau's methods
and assumptions and, after the Bureau made a number of revisions in
response to our questions, found that the revised data produced were
generally reasonable to use to project the possible effects of the
Bureau's proposed sampling and statistical estimation initiatives. 
The results of the simulations show that the Bureau's plan, if
effectively implemented, has the potential for producing a more
accurate and less costly census than if only conventional census
procedures were used.  According to the Bureau's cost estimates,
which are shown in table 1, using the Bureau's refined plan for the
2000 Census would save between $700 million and $800 million off the
cost of using a plan that incorporated all of the new initiatives
proposed for the 2000 Census except those involving sampling and
statistical estimation. 



                                Table 1
                
                  Comparison of Estimated 2000 Census
                 Costs for Selected Design Alternatives

                         (Dollars in billions)

Design                                                    Cost in 2000
alternatives   Description                                   dollars\a
-------------  ----------------------------------------  -------------
Bureau's       --Include all planned improvements of             $ 4.0
 refined plan   1990 procedures;
 for 2000       --sample nonrespondents directly after
 Census (as     mail return phase to achieve a
 of March       90-percent response for each census
 1997)          tract, then use sample data for
                remaining nonrespondents;
                --use ICM to complete the census.
90-Percent     --Include all planned improvements of               4.2
 truncation     1990 procedures;
 for            --use conventional nonresponse follow-
 nonresponse    up until achieving 90-percent
 follow-up      response for each census tract; then
                sample remaining
                nonrespondents;
                --use ICM to complete the census.
Time           --Include all planned improvements of               4.6
 truncation     1990 procedures;
 for            --use conventional nonresponse follow-
 nonresponse    up for a set period of time,
 follow-up      then sample remaining nonrespondents to
                achieve a 90-percent
                response rate for each census tract;
                --use ICM to complete the census.
Conduct 2000   --Do not use sampling for nonresponse               4.4
 Census         follow-up;
 without        --include all other planned
 sampling for   improvements of 1990 Census
 nonresponse    procedures,
 follow-up      including ICM to complete the census.
Conduct 2000   --Do not use sampling for nonresponse           4.7-4.8
 Census         follow-up or ICM;
 without        --include all other planned
 sampling for   improvements of 1990 procedures;
 nonresponse    --use increased activities (e.g.,
 follow-up or   publicity, follow-up of vacant housing
 ICM            units) to attempt to achieve census
                coverage consistent
                with 1990 levels;
                --use a PES only to evaluate the
                quality of the
                census.
----------------------------------------------------------------------
Note 1:  Planned improvements of 1990 procedures include initiatives
such as the multiple mail strategy, questionnaire redesign, enhanced
outreach and promotion, sampling for nonresponse follow-up, and ICM. 

Note 2:  All design alternatives assume an overall mail response rate
of about 67 percent. 

\a Bureau cost estimates are as of June 1997 and are subject to
revision. 

Source:  Census Bureau data. 

The Bureau provided us with results from its computer simulations of
what could be produced in the 2000 Census using its refined design
for 2000 (i.e., using direct sampling controlled at the census tract
level for nonresponse follow-up together with ICM).  Those research
results indicated that, relative to the size of the population being
estimated, the new methods proposed by the Bureau would likely result
in less relative error in census data for the nation, states,
congressional districts, and most census tracts than using a
conventional census design (see fig.  2).\12 Because of the
limitations of the research we reviewed, these numbers only serve as
an illustration of likely results in 2000.  Despite these caveats,
results near these levels would represent a reduction in the relative
error rates experienced in the 1990 Census. 

   Figure 2:  Simulations Indicate
   Bureau's Refined Design Could
   Produce Lower Relative Error
   Rates Than a No Sampling Design
   in 2000

   (See figure in printed
   edition.)

Note 1:  The average relative error is shown for each geographic
level. 

Note 2:  Relative error for the no sampling design (i.e.,
implementing all planned improvements of 1990 procedures except
sampling for nonresponse follow-up and ICM) is the projected net
undercount rate in the 2000 Census. 

Note 3:  Relative error for the direct sampling design combines the
sampling error from sampling for nonresponse follow-up and ICM. 

Note 4:  Data for states exclude Washington, D.C. 

Note 5:  Data do not include possible errors from other sources, such
as any bias in the statistical models used to produce the population
estimates. 

Source:  Census Bureau data. 

The Bureau's simulation results for design alternatives also
illustrated one of the major trade-offs in accuracy between designs
that use sampling and statistical estimation and those that do not. 
The simulation results suggest that the new statistical methods the
Bureau proposes to use in the 2000 Census would likely produce
results that appear more accurate or more equitable according to at
least three broad criteria:  (1) better average levels of error, (2)
error distributions compressed closer to the average levels, and (3)
an apparently better cumulative error distribution.  For example,
state population totals, which are the basis for apportioning seats
in the House of Representatives, not only show lower error rates on
average but also show much less variation in the error rates among
states when compared to the undercount rates in the 1990 Census. 

The results also showed, however, that some areas that may have very
low net error rates using a conventional census design could have
higher error rates if sampling for nonresponse and ICM are used,
particularly as smaller geographic levels are considered.  The
smallest geographic areas for which detailed data from the Bureau
simulations are available are census tracts.  The Bureau projected
that its refined plan for the 2000 Census, using the direct sampling
option for nonresponse follow-up, would have an average error rate of
1.1 percent for census tracts.  The average error rates were 1.5
percent for the nonresponse follow-up option, using 90-percent
truncation, and 1.3 percent, using the time-truncation option.  The
estimated average net undercount for tracts using conventional
procedures was 1.9 percent.  The Bureau calculated that its refined
plan for 2000 would produce less error for 64 percent of census
tracts.  For the other two options the Bureau considered
implementing, the simulations indicated that the time-truncation
option would produce less error for 54 percent of the tracts and that
the 90-percent truncation would produce less error for 51 percent of
the tracts.  The converse of these data is that the conventional
procedures were projected to perform better for around 40 to 50
percent of the tracts, depending on the option used for comparison. 
(For more detailed information on projected error levels, using these
alternative census designs, see apps.  I and II.) The Bureau intends
to contract for a study of the potential block-level effects of using
sampling. 

Technically, the most accurate design alternative, according to the
results of the Bureau's research, would be to attempt 100-percent
follow-up of nonrespondents and use ICM to address accuracy problems. 
That design could produce slightly improved accuracy in census data,
particularly for smaller geographic areas, but would come at a
greater cost (approximately $400 million more than that for the
Bureau's refined plan).  Furthermore, such an option may not be
feasible given projected staffing difficulties and, especially, the
risk that the Bureau could not complete 100-percent follow-up and ICM
by the December 31 deadline for reporting census results for
congressional reapportionment.  The results of the Bureau's research
on alternative sampling approaches are included in appendixes I and
II. 


--------------------
\12 In this report, we primarily use relative error to enable us to
compare results of different design alternatives and geographic areas
with differing population sizes.  The Bureau's simulations measured
two different types of error:  sampling error for the Bureau's
alternatives that incorporate sampling for nonresponse follow-up and
ICM and net undercount or overcount for conventional census design
alternatives. 


         CONSTITUTIONAL AND LEGAL
         ISSUES
-------------------------------------------------------- Letter :5.3.1

The use of sampling in connection with the decennial census count has
been questioned on constitutional and statutory grounds.  Article I,
section 2 of the Constitution requires an "actual Enumeration" of the
population every 10 years and vests Congress with the authority to
conduct that census "in such a Manner as they shall by Law direct."
Congress has, in turn, delegated this authority to the Department of
Commerce through the Census Act.\13 One of the key issues in the
constitutional debate on sampling is whether sampling would be
considered an "actual Enumeration" as required by article I, section
2.  The Supreme Court has never considered the specific issue of
whether the use of sampling violates the Constitution.  The Court
has, however, considered various constitutional challenges to the
conduct of the census in other contexts. 

Most recently, the Court determined that the Secretary of Commerce's
decision not to use a post-enumeration statistical adjustment in the
Department's final census count in 1990 was within the constitutional
bounds of discretion that the Secretary has over the conduct of the
census.\14 The Court specifically stated in the decision that it was
"not decid[ing] whether the Constitution might prohibit Congress from
conducting the type of statistical adjustment considered here."\15 In
that case, the Court, citing its previous decisions concerning census
issues, concluded that so long as the Secretary's conduct of the
census is "consistent with the constitutional language and the
constitutional goal of equal representation," it is within the limits
of the Constitution.\16 The Court based its deference to the
Secretary's action on "the wide discretion bestowed by the
Constitution upon Congress, and by Congress upon the Secretary."\17

While, as noted earlier, this decision did not address whether
statistical adjustments were constitutionally permissible, proponents
of sampling have argued that the Court's recognition of the
considerable discretion granted Congress and, by delegation, the
Secretary of Commerce, to conduct the census would support the use of
sampling if the Secretary determined sampling was necessary to
produce a more accurate count of the population than would result
from a bare headcount.  Alternatively, opponents of sampling have
argued for a more literal interpretation of the phrase "actual
Enumeration" in the Constitution and point to dissatisfaction with
the initial congressional apportionment (which has been described as
a "conjectural ratio") and to the consistent practice of using
unadjusted headcounts from the first census in 1790 until recent
decades. 

There is also a controversy concerning the application of specific
statutory provisions to sampling.  The Census Act states that the
Secretary of Commerce is to undertake a decennial census "in such
form and content as he may determine, including the use of sampling
procedures." However, another section of the act\18 appears to
restrict the use of sampling as follows: 

     "[e]xcept for the determination of population for purposes of
     apportionment of Representatives in Congress among the several
     States, the Secretary shall, if he considers it feasible,
     authorize the use of the statistical method known as "sampling"
     in carrying out the provisions of this title." (emphasis added)

The language and legislative history of these statutory provisions
has been the subject of debate on the issue as to what, if any,
limits on the use of sampling were envisioned by Congress.  Judicial
interpretation of the statutory provisions has been confined to lower
courts and has generally supported the conclusion that section 195
permits adjustment for apportionment purposes.\19 The question of
whether sampling is statutorily and constitutionally permissible in
determining the decennial census count can only be definitively
resolved by the Supreme Court. 


--------------------
\13 13 U.S.C.  141(a). 

\14 Wisconsin v.  City of New York, 116 S.  Ct.  1091 (1996). 

\15 [Id., at 1101.]

\16 [Id.]

\17 [Id., at 1103.]

\18 13 U.S.C.  195. 

\19 See, e.g., City of Philadelphia v.  Klutznick, 503 F.  Supp.  663
(E.D.  Pa.  1980); Young v.  Klutznick, 497 F.  Supp.  1318 (E.D. 
Mich.  1980). 


   RISK OF A FAILED CENSUS IN 2000
   HAS INCREASED
------------------------------------------------------------ Letter :6

The 1990 Census was more costly yet less accurate than the 1980
census.  By 1994, the fundamental design of the 1990 Census had been
found to be flawed and in need of change.  This conclusion was
reached independently by the Department of Commerce task force for
designing the 2000 Decennial Census; two expert panels of the
National Academy of Sciences, one of which was commissioned by
Congress to study the 1990 Census; the Bureau; and us.  As a result
of this conclusion, the Bureau was faced with the question of how
best to change the conventional census-taking methods in a manner
that would make them less costly and more accurate than the 1990
Census and would meet the approval of stakeholders, including
Congress, federal agencies, state and local governments, the public,
demographers, and others who rely on census information. 

Planning a decennial census that is acceptable to all of these
stakeholders includes analyzing the lessons learned from past
practices, identifying those initiatives that show promise for
producing a better census at lower cost, testing those initiatives to
determine their effectiveness and feasibility, and convincing
stakeholders of the value of the proposed changes.  Although the
Bureau has generally been responsive to concerns, suggestions, and
recommendations made by us and others, it has not been able to
convince all of its key stakeholders, particularly Congress, of the
value and acceptability of its plans and proposals for improving the
design of the 2000 Census.  Since our October 1995 testimony,
significant congressional opposition to the Bureau's census design
has surfaced, and Members of Congress have raised questions about the
level of funding being requested for the census.  However, the Bureau
has said that the alternative of returning to the conventional census
design (i.e., without methods improvements, sampling for
nonresponding housing units, or ICM) that failed to include more than
4 million people in 1990 and would miss at least 5 million people in
2000 is not an alternative.  Thus, in February 1997, this uncertainty
over design and funding levels, at this late stage of census
preparation, led us to designate the 2000 Census as being at high
risk for wasted expenditures and unsatisfactory results.\20

At least two factors have contributed to the Bureau's inability to
reach agreement with Congress.  First, the Bureau has not always
provided sufficient information to Congress or others to support its
initiatives.  Specifically, the Bureau has not provided (1) enough
detailed data to show the range and distribution of effects that its
initiatives are designed to achieve and (2) the results of its
research to address concerns about the soundness or subjectivity
associated with its proposed statistical methods.  Second, the Bureau
has neither successfully tested the operational feasibility of some
key initiatives it would implement in 2000 nor yet determined how
well all these initiatives work together.  This situation contributes
to uncertainty over whether the Bureau's plans can be successfully
carried out. 


--------------------
\20 GAO/HR-97-2, February 1997, pp.  141-146. 


      NEED EXISTS FOR MORE
      DETAILED INFORMATION AND
      DATA TO SUPPORT KEY BUREAU
      PROPOSALS
---------------------------------------------------------- Letter :6.1

Over the last few years, the Bureau has provided general data on the
anticipated mail response rates to questionnaires, the accuracy of
the census data, and the estimated cost of and dollar savings from
its initiatives.  However, it has not always provided sufficiently
detailed data on the expected effects of its initiatives on such key
variables as the accuracy or equity of census data.  This lack of
sufficient data on expected effects has made it difficult for
Congress and other stakeholders to support Bureau initiatives. 

The Bureau's proposal to expand the use of statistical sampling and
estimation procedures to handle the workload resulting from
nonresponding housing units is an example of a proposal for which the
Bureau did not provide sufficiently detailed data.  When we testified
in October 1995, the Bureau was studying alternative sampling
designs.  Although we supported the concept of using statistical
sampling and estimation methods, we noted that further study of the
alternatives was necessary.  In the same congressional hearing, the
Director of the Census Bureau testified that the Bureau would
continue its research and provide details of the Bureau's plans,
including details on alternatives for sampling nonresponding housing
units and for statistical estimation procedures. 

In February 1996, the Director of the Bureau, the Secretary of
Commerce, and the Director of OMB, among others, presented the
Bureau's overall plans for the 2000 Decennial Census.  The sampling
initiative the Bureau selected involved a 90-percent truncation
design that would be controlled at the county level.  The Bureau
continued to say that a design employing the truncation option for
nonresponse follow-up, together with ICM, was the superior
alternative.  However, the Bureau provided no additional details
about the effects of the selected option or of the other alternatives
on census accuracy or equity. 

The Bureau's plan for the 2000 Census was not well received by the
House Committee on Government Reform and Oversight and certain other
stakeholders who were concerned about the effects of this plan on the
accuracy and equity of the census.  At hearings held the day after
the Bureau presented its plans, several witnesses testified that the
plan was unacceptable.  One concern was that sampling at the county
level would cause a deterioration in the accuracy of the counts of
minorities. 

On September 16, 1996, the Bureau announced a revision to its plan to
control sampling of nonresponding housing units at the county level,
stating that it would sample at the tract level.  However, the Bureau
provided only limited additional data that would enable Congress and
other stakeholders to gauge the impact of the revised proposal on
accuracy and equity.  In general, the data were summary statistics
showing the average error rates at various geographic levels.  When
the Bureau provided additional information on ranges of error rates
at different geographic levels, it did not provide the supporting
details.  In particular, the Bureau did not provide the details on
the distribution of errors across geographic areas, such as states or
tracts.  Such details would help show whether the potential error
rates for most areas were close to reported averages or distributed
more widely across the range of errors.  They would also help
identify the number of geographic areas with potentially high error
rates and whether they were scattered across the country or clustered
in certain areas. 

On September 24, 1996, the House Committee on Government Reform and
Oversight issued a report that was critical of the Bureau's
initiatives for sampling and statistical estimation.  Among other
things, the Committee found that the Bureau had not clarified issues
of accuracy, particularly for small geographic areas, raised by the
sampling initiative.  The Committee also raised concerns about the
operational feasibility of, and possible subjectivity associated
with, the Bureau's proposed sampling and estimation procedures.  It
also found that views differed on the constitutionality and legality
of using the proposed sampling and estimation procedures,
particularly with regard to apportionment.  The Committee recommended
that the Bureau not use sampling and estimation procedures to
complete or adjust the census. 

In December 1996, we met with Bureau officials to discuss the need
for and importance of having sufficient information on the potential
effects that its proposed sampling and estimation initiatives would
have on accuracy and equity.  The Bureau officials said that they had
been reluctant to release detailed draft data while research was
under way because of concerns about criticisms the Bureau may face if
the numbers changed on the basis of subsequent research results. 
However, the officials agreed that they needed to provide these data
and expedited their efforts to do so.  In December 1996 and January
1997, the Bureau provided us with detailed data on the results of its
simulations.  Although these were draft data, they compared the
potential effects on accuracy at various geographic levels that could
be produced using various design alternatives proposed for the 2000
Census.  However, in a February 1997 response to the concerns of the
House Committee, the Bureau provided neither these nor other detailed
data to address the Committee's concerns about the effects of the
planned sampling and estimation procedures. 

On April 2, 1997, we provided the Bureau with a draft of this report
for comment.  In attempting to verify the data and other information
that they had provided us for the report, Bureau officials discovered
some discrepancies and other errors.  For example, there were some
inconsistencies in the data displayed in the chart the Bureau had
been using to summarize the potential costs and accuracy of
alternative census designs.  (The revised chart appears as fig. 
II.1.) Most columns in the chart presented projected results for the
2000 Census, but the tract-level data represented a simulation of
results for the 1990 Census.  Bureau officials also discovered a
problem in the data files used to simulate the results for those
census designs that did not involve sampling or statistical
estimation; this problem increased the reported error rates at the
census tract level for those designs.  The cost estimate for the
design alternative using direct sampling for nonresponse (the
Bureau's refined plan) was also understated because the Bureau had
not revised its estimate to account for the cost of changing from a
nonresponse follow-up based on county-level response rates to one
based on tract-level rates. 

The Bureau notified us about these data problems and mistakes later
in April 1997 and began to rerun the data we had requested.  However,
the Bureau was not able to provide us with a final version of the
revised information and data sets until June 1997.  The revised data
addressed the problems identified in April by consistently presenting
projected results for the 2000 Census, including revised cost
estimates.  While we waited for the revised data, which should be
shared with all stakeholders, Public Law 105-18 was enacted,
requiring Commerce to provide Congress with a comprehensive and
detailed plan outlining its proposed methodologies for conducting the
2000 Decennial Census. 

Another example of the Bureau's not providing detailed data on the
expected effects of a Bureau initiative involves congressional
concerns about the subjectivity associated with the Bureau's sampling
plans.  In its September 1996 report, the House Committee on
Government Reform and Oversight raised concerns about the
subjectivity associated with such decisions as the selection of the
samples the Bureau intends to use for nonresponse follow-up and for
ICM.  The final details of the Bureau's methods and procedures could
affect the census results, and this is especially important since the
formula used to apportion seats in the House of Representatives is
mathematically very sensitive to the number of people in states that
may receive the last few seats through the apportionment process. 
However, in its February 1997 response to the House Committee on
Government Reform and Oversight, the Bureau did not provide specific
information on how it would make many decisions, such as sample
selections.  Without information on the census design options
considered, their likely implications, the choices the Bureau made,
and the bases for such choices, Congress and other stakeholders may
continue to have concerns over subjectivity in the 2000 Census. 

The Bureau also has not provided detailed justification for its
proposed initiative for a $100 million advertising campaign,
concerning its effects on cost and response rates.  Previously, the
Advertising Council had conducted a public service advertising
campaign for the census at no cost to the Bureau.  Although we share
the Bureau's hope that its planned advertising campaign will increase
mail response rates, the Bureau has provided no detailed data linking
expenditures on advertising with a corresponding increase in public
response.  Although it may be impossible for the Bureau to predict
precisely the increase in the response rate that paid advertising may
produce, as of June 20, 1997, the Bureau had not provided data
supporting the budget of its proposed $100 million advertising
campaign.  In the recent 1996 election, hundreds of millions of
dollars were spent not only to promote the candidates, but also in a
public service advertising effort to promote voting to specific
groups, such as 18-to 25-year-olds, who were targeted by rock stars
and other celebrities on radio, television, and cable television
channels using the slogan "Rock the Vote." Nevertheless, under 50
percent of the voting age population turned out to vote.  Although
differences exist between filling out a census questionnaire that is
sent to one's home and either getting to a polling place or arranging
to vote at home, both require responses motivated by civic
involvement.  Although about 93 percent of those surveyed on the 1990
Census were aware of it, only 65 percent of those households that
received questionnaires by mail responded.  Thus, a question is
raised about the effectiveness of paid advertising in stimulating
action as opposed to simply raising awareness.  The Bureau is
planning to evaluate its proposed advertising campaign in the Census
2000 Dress Rehearsal, but it is not yet clear how much money Congress
will provide for this evaluation. 

Finally, in March 1997, Bureau officials said that, as part of its
multiple mail contact initiative, the Bureau plans to send
replacement questionnaires to all housing units, as opposed to (as
planned) just those that did not return the original questionnaire. 
However, the Bureau did not release data on the costs or benefits of
this change, which would result in the Bureau's mailing two
questionnaires to about 97.3 million households in 2000, about 59.5
million of which may already have returned a questionnaire.\21


--------------------
\21 The Bureau anticipates mailing questionnaires to about 82 percent
of housing units and plans to use other procedures for obtaining
responses from the remaining housing units.  If the Bureau finds
concentrations of new city-style addresses during its address list
development process, it may add them to the percentage of housing
units that are to receive a questionnaire by mail in 2000. 


      QUESTIONS REMAIN ABOUT THE
      OPERATIONAL FEASIBILITY OF
      SOME ASPECTS OF THE BUREAU'S
      REFINED PLAN
---------------------------------------------------------- Letter :6.2

Members of Congress have questioned whether the Bureau can
successfully implement some aspects of its current plan for the 2000
Census.  They have also raised concerns about the Bureau's proposal
to incorporate an adjustment into its basic counting process, citing
issues of subjectivity and potential error associated with such an
adjustment.  Because the Bureau has not tested some aspects of its
currently proposed plan and has not tested whether all aspects of
this plan will work in concert with each other, there is uncertainty
as to whether or how well the Bureau's plan can be carried out. 

Field testing enables the Bureau, as well as Congress and other
stakeholders, to assess the operational feasibility of key
initiatives of its plans.  The Bureau has been evaluating features of
its proposed census design in a variety of tests over the past few
years and plans to do more testing before 2000.  For example, the
Bureau did a test census in 1995 and began another test, primarily of
its proposed coverage measurement survey and estimation methods
(ICM), in October 1996.  However, some operational aspects of the
current census design have not yet been fully tested successfully or
have not yet been tested in a manner similar to the implementation
being proposed for 2000. 

For example, the Bureau's current plan depends on completing sampling
for nonresponse follow-up and ICM in time to produce the population
count by December 31, 2000.  However, the 1995 Census Test did not
test a sampling operation designed to help determine whether
nonresponse follow-up of the magnitude projected by the Bureau's
current plan could be completed in time for ICM to be done on
schedule.  While the Bureau did use a version of direct sampling for
nonresponse follow-up in the 1995 Census Test, it was not designed to
achieve at least a 90-percent completion rate before the Bureau
relied on sample data to account for the remaining nonrespondents. 

In order to do ICM more rapidly, the Bureau plans to use laptop
computers in the field.  However, during the 1995 Census Test, the
Bureau had difficulty loading data from nonresponse follow-up
activities into the laptop computers in time for use by enumerators
doing ICM interviews.  As a result, enumerators, were unable to match
interview data with original census questionnaire data, which
prevented them from resolving discrepancies as originally planned. 
The Bureau revised the procedure and its software to correct earlier
problems, began to retest this operation in early 1997, and is
continuing to work on the procedures and software to be used for
computerized matching of housing units and individuals listed by ICM
and other census operations. 

Another aspect of the current plan that has yet to be tested is the
operation of the scanning equipment for the 2000 Census that will be
used to capture data on census forms.  Although the Bureau used some
scanning in the 1990 Census (i.e., multistage photoimaging equipment
that turned photographs into microfiche and, in turn, into tapes), it
is planning to use more sophisticated scanning equipment that can
"read" handwritten material and convert it directly into a
machine-readable format, as well as a more extensive use of scanning,
in 2000.  The Bureau used a prototype scanning system and optical
character reader in parallel with the 1995 Census Test.  The
successful operation of this equipment is critical to the Bureau's
plan because its ICM procedure depends on the availability of
accurate information.  The Bureau has been developing the equipment
with a contractor and plans to have a prototype ready for testing in
the Census 2000 Dress Rehearsal in 1998.  At this time, however, it
is not clear that this test will be sufficient for determining
whether the equipment can successfully handle the volume of forms
that will be processed in 2000.  If the equipment cannot or does not
work out as expected, the Bureau proposes using a keypunching
operation, which would be considerably slower than the scanning
alternative and could cost more to complete the task. 

According to the Bureau, the Census 2000 Dress Rehearsal is to
provide a census-like environment to demonstrate simultaneously those
procedures that the Bureau plans to use in the 2000 Census.  A
meaningful dress rehearsal is important for at least three reasons. 
First, the Bureau plans to implement several complex new design
features in 2000, including the use of technologically sophisticated
equipment that has not been used in previous censuses.  Second,
Congress and the Bureau have yet to reach agreement on the 2000
Census design, and uncertainty over the operational feasibility of
the Bureau's design was one of Congress' major concerns.  Third, a
key feature of the Bureau's current plan is to produce a one-number
census by using sampling and statistical estimation. 

Thus far, the Bureau has not fully tested its proposed design, and
the Census 2000 Dress Rehearsal is the last opportunity for such
full-scale testing.  While the Bureau provided us with projected
results from simulations of its design, the Dress Rehearsal would
provide an opportunity to determine whether the Bureau's refined plan
would actually produce similar results when implemented in the field. 
Implementing the 2000 Census without adequate testing creates the
risk of a census with unsatisfactory results.  Similarly, if the
Bureau implements its current plan in 2000 and Congress were to
decide after the Census 2000 Dress Rehearsal that it did not want the
Bureau to make an adjustment to its initial count, substantial funds
could be wasted, and the census results could be questionable. 

The Bureau has time before the 2000 Census is to begin to resolve
open issues and test much of what it actually plans to implement in
2000.  However, the available time is diminishing, and the Bureau has
not yet completed detailed planning for all of its design features or
its dress rehearsal.  The Census 2000 Dress Rehearsal appears to be
the last real chance the Bureau will have for a large-scale
operational test of its overall design.  Thus, a well planned and
executed dress rehearsal should provide the Bureau with a good
opportunity to demonstrate to Congress and others whether or not it
can successfully implement its current plan and produce acceptable
results.  The need for this demonstration is particularly important
considering the problems the Bureau has experienced to date and the
controversy that surrounds its design. 


   CONCLUSIONS
------------------------------------------------------------ Letter :7

The Bureau has made considerable progress in preparing for the 2000
Census since our October 1995 testimony.  The Bureau has, however,
revised some of its initial plans and encountered problems involving
some aspects of its proposed design.  For example, it has changed its
plan for sending replacement questionnaires to just those housing
units that did not return the original questionnaire.  Instead, it
now plans to send replacement questionnaires to all housing units. 
Most importantly, it has run into major opposition from Congress on
its plans to use sampling for nonresponse follow-up and ICM, and
consequently it is still not certain how much funding will be made
available.  This situation creates a high risk to the nation of a
census involving wasted expenditures and unsatisfactory results. 

Two of the major reasons for congressional concern are the lack of
sufficiently detailed data, particularly on the effects on accuracy
and equity of the Bureau's proposals for sampling for nonresponse and
ICM, and the uncertainty surrounding the operational feasibility of
key aspects of the Bureau's current census design.  We recognize that
the Bureau has faced difficulties as it has tried to address the
concerns of all its stakeholders--who at times have had conflicting
views--and as some aspects of its plan have not worked out as well as
expected during testing.  Although the Bureau faces a risk if it
provides draft data while research is under way, we believe that
Congress and other stakeholders would benefit from having the best
data available at the time Bureau proposals are made, along with the
appropriate qualifications. 

Full and open disclosure is the only possible antidote to suspicions
that the Bureau is failing to fully inform its legitimate
stakeholders.  Since one of the purposes of testing is to determine
the operational feasibility of plans, it should not be surprising
that problems arise.  No design is without flaws and trade-offs.  The
Bureau has said that the alternative to its proposed design is to
return to past census methods and incorporate changes, such as
initiatives to improve the response rate, but not sampling for
nonresponse follow-up or ICM.  In this regard, data on the costs and
effects of that alternative would be helpful in considering whether
the Bureau's proposal should be approved.  However, the Bureau has
not provided Congress with these data. 

By not providing sufficient data on the likely effects of the
Bureau's initiatives for addressing the key goals for the
census--reduced costs and improved accuracy and equity--the Bureau
may fail to convincingly demonstrate the value of its plans and, in
turn, may contribute to congressional skepticism about census design
and the necessary funding level.  Through the enactment of Public Law
105-18, Commerce is now required to supply data by July 12th on the
likely effects of the census design, which should contribute to a
more informed debate.  However, as new data become available after
July 12th, they also should be shared with Congress and other
stakeholders. 

The Census 2000 Dress Rehearsal offers a final opportunity for the
Bureau to demonstrate the operational feasibility of its current
plan, which proposes many new design initiatives for the 2000 Census. 
If in the dress rehearsal the Bureau does not demonstrate that all of
the key initiatives of the design that are to be used in 2000 can
successfully be implemented to produce acceptable results, it risks a
census with higher rates of error than in 1990 as well as higher
costs. 

With less than 3 years remaining until the census is to take place,
the Bureau and Congress are not yet in agreement on some basic census
design issues and the overall funding level.  Although we believe
there is still sufficient time for agreement to be reached and for
the Bureau to prepare for a successful census, little margin for
missteps, indecision, or miscommunication remains. 


   RECOMMENDATIONS TO THE
   DIRECTOR, BUREAU OF THE CENSUS
------------------------------------------------------------ Letter :8

We recommend that the Director of the Bureau of the Census

  -- provide Congress and other stakeholders with detailed data,
     which are updated as necessary to meet the objective of full and
     open disclosure, on the expected effects of the Bureau's census
     design proposals on costs and on accuracy and equity at various
     geographic levels, particularly as they relate to sampling for
     nonresponse and ICM as well as on a design that would not
     involve sampling nonrespondents and ICM;

  -- work with Department of Commerce and OMB officials in reaching
     agreement with Congress on the design and funding level as
     quickly as possible, so that the Census 2000 Dress Rehearsal can
     be used to demonstrate all key design features planned for the
     2000 Census; and

  -- conduct the Census 2000 Dress Rehearsal to mirror as closely as
     possible the design features planned for the 2000 Census,
     including paid advertising, to test the operational feasibility
     of the design and to determine whether the outcomes achieved in
     the dress rehearsal are similar to those of the Bureau's
     research and simulations, and provide these results to Congress
     in sufficient time to enable it to affect, if it so chooses, the
     final design for the 2000 Census. 


   AGENCY COMMENTS AND OUR
   EVALUATION
------------------------------------------------------------ Letter :9

On April 2, 1997, we requested comments on a draft of this report
from the Secretary of Commerce.  On April 23, 1997, the Director of
the Bureau of the Census responded that she agreed with our
recommendations.  She said that the Bureau had begun an intensive
effort to improve communications with Congress and demonstrate
responsiveness by providing the information Congress needs to assess
the value of the Bureau's plans for Census 2000.  She also said that
the Bureau expects these improved communications to lead to agreement
on the plan for conducting the Census 2000 Dress Rehearsal as a means
to demonstrate the robustness of the methods proposed for use in
Census 2000. 

The Director also stated that, in reviewing our draft report, the
Bureau was alerted to several inconsistencies in the data it had
provided us and on which we relied in making our analysis.  She said
the Bureau would regenerate the data.  These data were provided to us
on June 16, 1997, and are included as appendix II.  Our report has
been modified to reflect the new data where appropriate.  The revised
data did not cause us to change our basic analysis and conclusions,
but they did reinforce the need, as expressed in our recommendations,
for the Bureau to expose the data relating to the effects of its plan
to broad scrutiny by Congress and other stakeholders. 

In view of the reporting requirements of Public Law 105-18, which was
enacted after the Director commented on our draft report, we modified
our recommendations slightly.  While we continue to believe the
Bureau should provide the details of its plans to Congress, we also
believe updated data should be provided as it becomes available,
beyond the reporting date established in Public Law 105-18. 


---------------------------------------------------------- Letter :9.1

We are sending copies of this report to the Chairman, Senate
Committee on Governmental Affairs; Chairman and Ranking Minority
Member, House Committee on Government Reform and Oversight; Director,
OMB; Secretary of Commerce; Director, Bureau of the Census; and other
interested parties.  Copies will be made available to others on
request. 


Please contact me on (202) 512-8676 or James H.  Burow, Assistant
Director, on (202) 512-3941 if you or your staff have any questions. 
Major contributors to this report are listed in appendix IV. 

Sincerely yours,

L.  Nye Stevens
Director
Federal Management and Workforce Issues


THE 2000 DECENNIAL CENSUS WITH
STATISTICAL SAMPLING AND
ESTIMATION:  AN OVERVIEW OF
OPERATIONAL AND TECHNICAL ISSUES
=========================================================== Appendix I

As part of our ongoing oversight of decennial census activities, and
in order to assist Congress in assessing the proposed design for the
2000 Census, we have been reviewing the Bureau's plans and efforts to
incorporate sampling for nonresponse follow-up and integrated
coverage measurement (ICM) procedures in the next census.  In this
appendix, we provide additional background and technical information
on the results of the Bureau's research on sampling and estimation
methods, such as the expected advantages, disadvantages, costs, and
benefits of different design options the Bureau has considered for
the 2000 Census.  The appendix is organized in three main sections. 
The first section presents information on sampling for nonresponse
follow-up, the second on ICM, and the third on the combined effects
of these proposed census procedures.  Appendix II presents the
Bureau's summary data on the projected costs and accuracy of its
current plan and alternative designs for the 2000 Census. 


   SAMPLING FOR NONRESPONSE
   FOLLOW-UP
--------------------------------------------------------- Appendix I:1

Declining rates of public response to the census have generated a
costly, time-consuming nonresponse follow-up workload for the Bureau. 
The Bureau is planning for many efforts in the 2000 Census to
encourage higher response rates and reduce its reliance on expensive
enumerator visits to every housing unit for which a census
questionnaire is not returned by mail.  However, the nonresponse
workload is still likely to be substantial.  Therefore, after making
what it believes are reasonable efforts to directly contact every
housing unit, the Bureau plans to sample a portion of the remaining
nonresponse units rather than continuing its efforts to complete
follow-up interviews for all of the nonresponse units as it has in
the past. 

The primary purposes of using sampling for nonresponse follow-up are
to save money and time.  The Bureau estimates that its current plan
for sampling during nonresponse follow-up operations could save about
$400 million in the 2000 Census off the cost of a census design
incorporating all other proposed improvements on the 1990 Census
model except sampling for nonresponse.  The use of sampling also
should enable the Bureau to complete follow-up operations more
quickly than in past censuses, which is essential if it hopes to
complete ICM operations and produce the census data by its legal
deadlines. 

The Bureau focused its research in this area on identifying and
refining the most promising options for sampling a portion of
nonrespondents after the initial mail return phase of the census is
completed.  On the basis of its initial work on this subject, the
Bureau decided in February 1996 that its plan for nonresponse
follow-up in the 2000 Census should ensure that it completes census
questionnaires for at least 90 percent of all housing units in each
county before using the information from sample units to account for
the remaining nonrespondents.  Public feedback and concerns about the
potential fairness and accuracy of this initial proposal persuaded
the Bureau to revise its plans in September 1996 to track response
rates and control nonresponse sampling at the level of census tracts,
which are generally smaller and more homogeneous than counties. 

Once the Bureau decided to control nonresponse sampling at the census
tract level, it began to study three options for how to implement
this basic design:  (1) truncating conventional follow-up interviews
after reaching the 90-percent completion threshold, then sampling the
remainder; (2) truncating conventional follow-up after a specific
period of time, then sampling the remainder; and (3) sampling
nonrespondents directly after the end of the mail return phase of the
census.  All three options are designed to collect information
directly for at least 90 percent of the housing units in each tract,
through a combination of mail returns, follow-up interviews, and
other means, before relying on sample data to estimate the population
counts and characteristics of the remaining nonrespondents.  The
Bureau's research indicated that implementing sampling directly after
the mail return phase would have more advantages than the other
options with regard to cost, accuracy, and operational feasibility. 
Therefore, in March 1997, the Bureau selected the direct sampling
option for nonresponse follow-up in the 2000 Census. 


      CENSUS NONRESPONSE GENERATES
      SUBSTANTIAL PROBLEMS FOR
      BUREAU
------------------------------------------------------- Appendix I:1.1

For the 2000 Census, the Bureau intends to rely on mail returns to
collect census data from most housing units in the country, as it has
in every census since 1970.  Unfortunately, census mail response
rates have been falling since the Bureau first implemented this
mail-back approach.  If past trends continue, the Bureau believes the
mail response rate could decline from the 65-percent rate achieved in
the 1990 Census to 55 percent in the 2000 Census, leaving over 50
million nonresponding units to account for. 

The declining rate of public cooperation with the decennial census
generated a substantial problem for the Bureau in 1990.  When
questionnaires were not returned for all housing units provided a
census form, the Bureau sent temporary enumerators out into the field
in an attempt to get data on each nonresponding unit.  This was an
extremely costly, time-consuming, and sometimes error-prone
operation.  In the 1990 Census, nonresponse follow-up operations
required a minimum of $560 million to carry out and continued for 14
weeks instead of the planned 6 weeks.  The delay in completing
nonresponse operations can be attributed in large part to the effort
needed to contact the relatively small portion of units that proved
most difficult to resolve.  This problem was widespread.  For half of
the census tracts in the country, once 90 percent of returns were in,
the Bureau still needed 65 days or more to finish collecting data on
the last 10 percent of housing units.  The Bureau's evaluations of
the 1990 Census demonstrated that the quality of these enumerations
declined substantially as data collection efforts continued over
time, (e.g., with regard to persons counted more than once, counted
in the wrong place, or missed entirely). 

The Bureau plans a number of efforts to encourage people to
voluntarily respond to the 2000 Census.  These efforts include
enhancements such as more user-friendly census forms, an improved
marketing plan, providing multiple ways for people to respond to the
census, and implementing a strategy of multiple mail contacts with
each address.  The Bureau estimates the combined effects of these
efforts will result in an increase of about 12 percent in baseline
response rates, projecting to an overall mail response rate of 66.9
percent in 2000.  However, even if these new efforts work as well as
planned, the Bureau would still face a substantial nonresponse
workload in the next census of nearly 40 million housing units.  This
would exceed the entire nonresponse workload of the 1990 Census by
approximately 5 million housing units. 

Handling a nonresponse follow-up workload of this size is likely to
pose a serious challenge to the Bureau in the 2000 Census.  Mail
response rates can vary dramatically among different areas of the
country, generating very large nonresponse workloads in some places. 
In addition, there is ample evidence that nonresponse follow-up is
becoming more expensive, not only because the number of
nonrespondents is growing, but also because (1) residents of
nonresponding housing units are becoming more difficult to find and
interview and (2) the Bureau is finding it harder to recruit and
afford enough qualified temporary workers to complete the task. 
Those problems, in turn, can contribute to escalating labor costs and
declining productivity during the census. 

Bureau officials believe that these problems, especially the
workforce difficulties they anticipate in the 2000 Census, suggest
that they could not use the 1990 Census design again even if they
wanted to.  They intend to implement a number of other efforts to
reduce the reliance on enumerator visits to each nonresponding
housing unit (e.g., attempting to cover more of these units through
telephone interviews).  Altogether, the variety of activities planned
for the next census should result in multiple efforts to directly
contact every housing unit, as well as multiple opportunities for
people to respond to the census.  However, Bureau officials still
believe that sampling a portion of nonrespondents will be necessary
to control the cost of the census and enable them to complete
follow-up operations in a timely manner. 


      BUREAU CONTINUES TO REFINE
      ALTERNATIVES FOR SAMPLING
      NONRESPONDENTS
------------------------------------------------------- Appendix I:1.2

The primary purposes of using sampling for nonresponse follow-up are
to save money and time.  After preliminary research efforts to
identify promising designs for sampling nonrespondents, Bureau
management announced in February 1996 selection of a 90-percent
truncation design for the Census 2000 plan.  Under this design, the
Bureau would implement a conventional nonresponse follow-up operation
at the end of the mail return phase of the census that would continue
until enumerators were able to obtain information for at least 90
percent of the housing units in each county or county-equivalent area
(such as parishes in Louisiana).  The Bureau would then truncate
(curtail) conventional follow-up operations and select a 1-in-10
sample of the remaining nonresponding units.  It would use the
information obtained from interviewing these sample units to provide
census data for the sample units themselves and also to estimate
population counts and characteristics for the remaining nonresponse
units. 

In September 1996, the Bureau revised its planned approach.  The new
design would control nonresponse sampling at the level of each census
tract--a small, relatively permanent statistical subdivision of a
county--rather than each county.\1 This plan maintained the overall
goal of collecting data on at least 90 percent of the housing units
in each area before relying on sampling to estimate data for the
remaining nonrespondents.  The Bureau made the change to tract-level
truncation in response to public feedback and reservations about the
potential effects of county-level truncation.  Stakeholders from
minority communities and others, including a National Academy of
Sciences panel, pointed out that areas within counties may often
differ in terms of how easy they are to enumerate, which could affect
the implementation of the Bureau's plan.  If the Bureau controlled
truncation at the county level, they noted the likelihood that the
threshold would be achieved disproportionately by mail responses and
direct follow-up interviews in the areas where enumeration was
easiest.  Sampling might then be relied upon for much more than just
the last 10 percent of households within the harder-to-enumerate
areas. 

The Bureau's shift to basing its plan on tract-level response rates
rather than county-level rates appears to improve the equity of the
sampling plan but also presents new challenges.  On balance, the
change to tract-level truncation may provide more equitable and
consistent implementation of sampling for nonresponse follow-up than
the original design.  This is primarily because the socioeconomic
characteristics of households at the tract level are more homogeneous
than is the case at the county level.  Therefore, sampling controlled
at the tract level is less likely to present a risk of uneven
implementation (i.e., ignoring hard-to-enumerate areas until the very
end of the census).  However, shifting to tract-level truncation also
complicates the task of managing and monitoring the nonresponse
follow-up phase, especially given that progress will need to be
tracked and controlled for around 60,000 census tracts nationwide,
compared to about 3,000 counties under the Bureau's original
proposal.  It may also increase the difficulty of reaching the goal
of a 90-percent completion rate in every tract, at any rate, within a
reasonable time frame. 

When the Bureau decided that its basic design for nonresponse
follow-up operations in the 2000 Census should ensure that it obtains
responses from at least 90 percent of all housing units in each
census tract before relying on the information from sample units to
account for the remaining nonrespondents, it began considering
alternative designs to achieve this goal.  The Bureau's research
focused on three design options:  (1) truncating conventional
follow-up at 90-percent completion, then sampling the remaining
nonrespondents; (2) truncating conventional follow-up after a
specific period of time, then sampling the remaining nonresponse
units; and (3) implementing sampling of nonresponding units directly
after the mail return phase ends. 

The first option was the Bureau's original design from February 1996,
except that it would track completion rates for each tract rather
than each county.  Under the time-truncation option, conventional
follow-up interviews would continue for a predetermined length of
time, such as 3 weeks.  After this initial follow-up period, the
Bureau would select a sample of the remaining nonrespondents in each
tract that included enough units to raise the completion rate to at
least 90 percent.  Under the direct-sampling option, there would be
no conventional follow-up phase.  Instead, at the end of the mail
return phase the Bureau would select a sample of the nonresponding
housing units in each tract that would be sufficient to achieve at
least a 90-percent completion rate.  For example, in a tract with a
mail response rate of 70 percent, the Bureau would select two out of
every three of the remaining units for the follow-up sample.  Under
each of the 3 options, for any tract with an initial response rate
above 90 percent the Bureau would follow up on a 1-in-10 sample of
the remaining addresses. 

Figure I.1 illustrates how each of these options might work in a
hypothetical census tract where the Bureau is able to obtain a mail
response rate of 60 percent.  In this simplified example, we show how
the Bureau would determine the census data for housing units in the
tract as it works toward resolving 100 percent of the units. 

   Figure I.1:  How Different
   Sampling Options Would Work in
   a Hypothetical Tract

   (See figure in printed
   edition.)

Note 1:  For all options, we assume a mail response rate for housing
units in the tract of 60 percent.  The base for this calculation
would be all housing units provided a census form and asked to return
it by mail. 

Note 2:  For the time-truncation option, we assume that the Bureau is
able to obtain responses from half of the nonrespondents during a
limited period of conventional follow-up interviews. 

Note 3:  Some of the units that make up the nonresponse workload will
be vacant or not be nonresidential units.  The Bureau expects that
the Postal Service will identify a portion of the vacant units in the
2000 Census (although the Bureau will recheck a sample of these).  To
simplify our presentation, we have not included any estimates for
this component. 

Source:  Example created by GAO for illustration purposes only. 

Under the 90-percent truncation option, and assuming that the tract
had a mail response rate of 60 percent, the Bureau would implement a
conventional nonresponse follow-up operation until enumerators were
able to get responses for another 30 percent of the housing units in
the tract (bringing the total completion rate for the tract up to 90
percent).  At that point, the Bureau would select a random sample at
the rate of 1 in 10 of the nonresponding units that still remained
unaccounted for.  The information gathered from that 1 percent of the
tract's housing units would provide the census data for the sample
units and the remaining 9 percent of the tract's units. 

Using the time-truncation option, there would be a limited period of
time, such as 3 weeks or until a prespecified date, during which
census enumerators would attempt follow-up visits to all
nonresponding units.  For our hypothetical example, we assume that
enumerators are able to complete interviews for half of the
nonresponding units during this initial follow-up phase, taking the
overall completion rate to 80 percent.  The Bureau would then need to
select and interview a sample of one of every two of the remaining
nonrespondents to achieve a completion rate of 90 percent.  The
information gathered from that 10 percent of the tract's housing
units would provide the census data for the sample units and for the
10 percent of nonresponding units that remain. 

With the direct sampling option in this scenario, the Bureau would
select a random sample at the rate of three of every four of the
nonresponding units in the tract at the end of the mail return phase. 
A sample of this size would be enough to get the overall completion
rate to 90 percent.  The information gathered from the 30 percent of
the tract's housing units in the sample would provide the census data
for the sample units themselves and for the remaining 10 percent of
units not selected for the sample. 


--------------------
\1 Census tracts usually have between 2,500 and 8,000
persons--averaging about 4,000--and, when first delineated, are
designed to be homogeneous with respect to population
characteristics, economic status, and living conditions.  Census
tracts do not cross county boundaries.  The 1990 Census included over
60,000 tracts and tract-equivalent areas. 


      RESEARCH IDENTIFIED
      POTENTIAL ADVANTAGES AND
      DISADVANTAGES OF ALTERNATIVE
      DESIGNS
------------------------------------------------------- Appendix I:1.3

The Bureau engaged in a variety of research efforts to study the
operations and potential outcomes of its planned approach for
conducting nonresponse follow-up in 2000, as well as other
alternatives.  The Bureau conducted field tests and evaluations of
various elements of nonresponse operations during the 1995 Census
Test.  The Bureau also carried out computer simulations, using 1990
data, to examine the results produced by various alternative methods
for nonresponse sampling.  The Bureau used these simulations to help
identify the sampling options that were most promising. 

In general, the Bureau's research confirmed the potential for
sampling to produce less costly, more timely results from nonresponse
follow-up.  The Bureau estimated that its current plan for the 2000
Census--using the direct sampling option for handling nonresponse
follow-up--could save approximately $400 million, when compared to
the cost of a census design incorporating all other planned
improvements of the 1990 Census design (including ICM) except
sampling for nonresponse follow-up.  Among the major factors driving
the cost differences are the number of nonresponding housing units
that the Bureau would need to visit under each design and the peak
staffing levels that would be required in the local census offices to
carry out the follow-up interviews. 

Completing nonresponse follow-up operations in a timely manner is
important if the Bureau is to limit the deterioration in the quality
of the data collected that occurs as nonresponse operations drag out
over time.  It is also crucial to the success of any coverage
measurement survey, such as the ICM proposed for the 2000 Census,
because the Bureau must provide the final census data for
reapportionment and redistricting purposes by legislatively mandated
deadlines.  Title 13 of the U.S.  Code mandates that the state
population totals required for reapportionment of the House of
Representatives be provided within 9 months after Census Day (April
1) and that local area data needed for redistricting be provided
within one year after the decennial census date.  The legal deadlines
the Bureau must meet are therefore December 31 of the census year for
reapportionment data and March 31 of the following year for
redistricting data. 

The 1995 Census Test demonstrated the potential to complete
nonresponse follow-up operations in a more timely manner by using
sampling.  In that test, the Bureau implemented a version of direct
sampling for nonresponse follow-up immediately after the completion
of mail return data collection.  The overall sampling rates used by
the Bureau in this test were two-sevenths of the housing units that
did not respond by mail in the Oakland, California, test site and
one-sixth of the nonresponding housing units for the test sites in
Paterson, New Jersey, and six parishes in Northwest Louisiana. 
According to Bureau officials, this approach enabled them to complete
nonresponse follow-up operations on time and within budget for the
first time in any census or test.  However, this direct sampling
approach did not require the Bureau to achieve at least a 90-percent
completion rate before relying on sample data to account for the
remaining nonrespondents.  Therefore, while the 1995 Census Test
results were encouraging, they did not resolve the question of
whether, using its selected option, the Bureau can complete
nonresponse follow-up in every tract on or close to schedule in the
2000 Census. 

The Bureau's initial efforts to study alternative designs for
sampling nonrespondents helped it reach a decision on the extent to
which it would use sampling in the 2000 Census.  On the basis of that
preliminary work, the Bureau proposed using a 90-percent truncation
design for nonresponse follow-up in the plan for the 2000 Census. 
Bureau management selected truncation at 90 percent as the preferred
design primarily because of concerns about whether the public would
understand and accept using sampling to a greater extent.  By
truncating conventional follow-up only after completing responses for
90 percent of housing units, then sampling the remaining units, the
Bureau would obtain direct responses for at least 91 percent of all
units.  Under other alternatives for nonresponse sampling that the
Bureau initially considered, such as truncating at 70-percent
completion then sampling, it would have obtained direct responses for
less than 80 percent of all housing units. 

After the Bureau revised its plan in September 1996 so that it would
control nonresponse follow-up at the tract level, subsequent research
focused on identifying the most promising design to achieve the
90-percent completion goal in each census tract.  The Bureau
identified advantages and disadvantages to each of the three design
options it considered--truncation at 90 percent, time truncation, and
direct sampling.  On balance, the Bureau's research indicated that
implementing sampling directly after the mail return phase would have
more advantages than the other options.  Therefore, in March 1997,
the Bureau selected the direct sampling option for nonresponse
follow-up in the 2000 Census. 

The Bureau's research suggested that a design using the direct
sampling option for nonresponse follow-up would be better than other
designs in terms of cost, accuracy, and operational feasibility. 
Bureau officials estimated the cost of implementing direct sampling
to be between $200 million and $600 million less than the cost of the
other two options they considered.  In simulations of the accuracy of
different options, direct sampling produced slightly better results,
particularly for small geographic areas, such as census tracts.  (We
discuss the expected accuracy of alternative census designs in more
detail in the last section of this appendix, and additional summary
information from the Bureau appears in app.  II.) The Bureau's
regional directors and field staff preferred this option because it
is simpler to implement, entails only one operation with a single
workload that is established at the start of the follow-up phase, and
provides more time to complete interviews for the designated sample
units.  The direct sampling design, however, differs most from the
design the Bureau originally announced as its plan for the next
census, as well as from the procedures used in past censuses.  In
addition, once the sample is selected, nonrespondents in housing
units not selected as part of the sample would not have another
chance to be interviewed by census enumerators.  Therefore, Bureau
officials believe this option could have some public-perception
problems. 

According to the Bureau, the time-truncation option may have an
advantage with regard to public perception because, under that
design, enumerators would make follow-up visits to all nonresponding
housing units in an intensive effort before sampling begins.  A time
truncation design should also take less time to finish than the
90-percent truncation design because conventional follow-up
interviews would automatically end on schedule, rather than continue
until the Bureau was able to resolve 90 percent of each tract's
housing units.  However, because it involves more than one follow-up
operation and workload, the time-truncation design is likely to take
more time than direct sampling.  The intensive initial follow-up
effort also makes time truncation more expensive than the other two
options for sampling nonrespondents.  The Bureau would need a large
number of temporary enumerators to attempt to contact every
nonresponding unit within the short period of conventional follow-up
interviews. 

Public perception was also the primary advantage identified by the
Bureau for the 90-percent truncation design.  Not only would it most
closely resemble past census procedures, but it is also the design
option that the Bureau has been discussing publicly since it
announced its original plan for the 2000 Census in February 1996. 
However, the Bureau's cost-model projections indicated that
truncating at 90-percent completion would be more costly than the
direct sampling option, and that this option also had the highest
average error rate for small neighborhoods, like tracts, in Bureau
simulations.  Also, the Bureau's regional directors believed that
accomplishing this design in the allotted time for nonresponse
follow-up operations would be very difficult.  Truncating at
90-percent completion, like the time-truncation option, separates
nonresponse follow-up into two operations.  The Bureau is concerned
that the break between conventional interviews and sample interviews
makes this design more complex and could result in higher staff
turnover. 


   INTEGRATED COVERAGE MEASUREMENT
--------------------------------------------------------- Appendix I:2

The purpose of ICM is to improve the accuracy of census data, in
particular by reducing the differential undercounts of minorities and
other hard-to-enumerate population groups and areas that have been
documented for previous censuses.  Evaluations of past censuses have
shown a persistent net undercount in the final census population
total and, for subnational data, net undercounts that differed across
population groups and geographic areas.  Evaluations also indicated
that simply adding more conventional counting operations was not
effective in eliminating or reducing these undercounts in the 1990
Census.  Therefore, the Bureau concluded that the 2000 Census design
should incorporate the results of a coverage measurement survey
conducted immediately following basic data collection as an integral
and necessary step toward completing the census. 

ICM would be the last phase in producing the final census numbers,
following mail returns and other basic data collection efforts,
nonresponse follow-up data from enumerator interviews, and
nonresponse sampling results.  During this last phase, the Bureau
would conduct a large sample survey to check the accuracy of all
earlier Census 2000 data collection efforts.  Bureau enumerators
would compare and reconcile the results from the ICM survey and the
earlier census efforts for each housing unit in the ICM sample to
determine the extent to which people and housing units were correctly
counted, missed, or included in error in the previous phases.  Using
statistical estimation methods, the Bureau would then use this
information to estimate and correct for errors in the census data for
the entire country. 

The Bureau designed the proposed 2000 ICM to address several major
weaknesses of the 1990 Post Enumeration Survey (PES), especially
regarding timeliness and the accuracy of population estimates for
subnational areas.\2 Because of these design changes, the 2000 Census
ICM would entail a substantial investment in resources, compared with
the 1990 PES.  It would also represent a dramatic shift in the
integral census operations because, rather than producing an
alternative adjusted set of census data, the results of ICM would
automatically be incorporated into one official set of census data. 
While results from research and testing to date indicate that ICM has
the potential to improve the accuracy of census data, they also show
that further operational and methodological testing and development
are needed before 2000. 


--------------------
\2 The 1990 PES was designed to estimate the net undercount in the
census.  It was a matching study in which the Bureau interviewed a
sample of households several months after the census.  The results of
these interviews were compared with census questionnaires to
determine whether each person was correctly counted in the census,
missed, or included in error.  The results could have been used to
adjust the 1990 Census to correct for coverage errors, if the
Secretary of Commerce had so decided. 


      PERSISTENT COVERAGE ERRORS
      AFFECT CENSUS ACCURACY AND
      EQUITY
------------------------------------------------------- Appendix I:2.1

One of the most fundamental criticisms of the census, and much of the
impetus behind efforts to redesign the census-taking approach, is
that it fails to count every area and population group equally well. 
Undercounts that are not equally distributed among geographical areas
and population groups can create inequities in political
representation and the distribution of public funds.  To be
equitable, it is not enough for a census to be generally accurate in
a strict numeric sense (i.e., that the total count be close to the
total U.S.  population).  For many uses of census data, including
reapportionment of congressional seats, legislative redistricting,
and some funds distribution, proportions matter more than the raw
totals.\3

Evaluations of past censuses have revealed persistent coverage
errors, such as net undercounts in the total population figures and
differential net undercounts in census data by race and geographic
area.  For the 1990 Census, the reported net undercount was about 1.8
percent of the population (4.7 million persons), according to
independent demographic analysis.\4 However, that does not mean that
over 98 percent of U.S.  residents were actually counted, as is often
reported, since the number of persons missed by the census was
partially offset in the net count by millions of persons who were
double counted or improperly included.  The PES indicated that about
6 million persons were counted twice in the 1990 Census, while 10
million were missed.\5 The 4.4 percent difference between the net
undercount for blacks (5.7 percent) and nonblacks (1.3 percent) in
1990 was the highest differential undercount measured by independent
demographic analysis since 1940. 

The Bureau's evaluations demonstrated that the 1990 Census missed
entire housing units (and their occupants), missed people within
housing units that it did count, and included other persons in the
population counts in error (e.g., by counting them more than once or
in the wrong place).  The detailed results from evaluations showed
that young adult males, members of ethnic and racial minorities, and
renters, among others, were more likely to be undercounted by the
census than other residents.  The difficulty of obtaining a complete,
accurate enumeration of the residents in major urban areas is well
known, but evaluations have consistently shown high error rates for
data on persons living in rural areas as well.  Error rates were also
demonstrably higher for persons counted on forms completed through
enumerator follow-up rather than mailed in by the household. 

The Bureau's research revealed many potential sources of coverage
errors.  For example, at the very start of the 1990 Census, the
address lists used to guide data collection were incomplete and had
other problems that made it difficult for the Bureau to deliver
questionnaires or attempt interviews with every housing unit.  In
addition, people moved during the census operations, which made it
more likely that some persons would be missed, counted more than
once, or counted in the wrong place.  Also, respondents and
enumerators sometimes had difficulty interpreting the residency rules
that determine whether and where people should be counted for census
purposes. 

Just as sampling for nonresponse follow-up is only one component of
the Bureau's strategy to handle the nonresponse problem, ICM is only
one element in the Bureau's plans to improve census accuracy and
reduce the differential undercount in 2000.  For example,
improvements in address list development and expanded partnerships
with other levels of government and community groups should identify
some housing units that the Bureau might otherwise miss.  To cite
another example, the Bureau intends to use special targeted methods
to improve the count of population groups and the count in geographic
areas in where the census has tended to miss a disproportionate share
of the people.  Altogether, the efforts planned for Census 2000
should result in the Bureau making multiple attempts to contact and
count all residents and should provide multiple opportunities for
people to respond to the census. 

However, even if all other design components produce improvements in
the conventional census counting operations, the evidence from past
coverage evaluations indicates that errors in the census data will
still occur.  Also, the task of accurately counting all members of
the population is becoming more difficult, in part due to a growing
population, but also as a reflection of the difficulty of having
census rules, definitions, and methods keep pace with changes in
society.  Bureau evaluations of the 1990 Census indicated that simply
adding more conventional counting operations was not effective in
eliminating or reducing differential undercounts of areas and
population groups that have been hard to enumerate accurately. 
Therefore, the Bureau and expert panels of the National Academy of
Sciences concluded that the 2000 Census design should incorporate the
results of a coverage measurement survey conducted immediately
following basic data collection as an integral and necessary step
toward completing the next census. 


--------------------
\3 Distributional accuracy, however, is not the only criterion for
the quality of census data.  For example, some applications use
specific population thresholds, such as those defining eligibility
for becoming a metropolitan area. 

\4 Demographic analysis provides an estimate of the population
derived largely from administrative data such as birth and death
records.  It is important because it provides an independent estimate
and a consistent historical series of data from 1940 to the present. 
However, its ability to produce reliable estimates below the national
level, or for components of the population other than black and
nonblack, is very limited. 

\5 In addition, evaluations revealed that about 2.4 percent of the
enumerated count in the 1990 Census represented persons who should
not have been counted at all (such as those who died before or were
born after census day, April 1) and those who should have been
counted at another address.  While some of these errors would not
affect the numeric total (e.g., as in the case of a person who was
missed at the address where he or she should have been counted, but
was included in error at another location), these types of errors
could affect the distribution and accuracy of population counts
reported for small areas, such as blocks. 


      PROPOSED ICM OPERATION
      INCLUDES MAJOR CHANGES FROM
      1990 PES
------------------------------------------------------- Appendix I:2.2

The purpose of ICM is to improve the accuracy of census data--in
particular, to reduce the differential undercount--rather than just
evaluate the quality of the data.  While the Bureau has evaluated the
magnitude and characteristics of census errors and undercounts since
1950, the evaluation findings have not been used to correct for
coverage errors in the decennial census tabulations.  A statistical
adjustment was considered after the 1990 Census, with the Bureau
using the results of the 1990 PES to produce a second, adjusted set
of census data.  However, upon review of the original census data and
the adjusted census data, the Secretary of Commerce found the
evidence in support of an adjustment to be inconclusive and
unconvincing and decided that the 1990 Census counts should not be
changed.  The Bureau's proposed design for the 2000 Census would
therefore mark the first time that such a step would be an integral
part of completing the census.  The ICM results would be the last
component in producing final census numbers, following mail returns
and other basic data collection efforts, nonresponse follow-up data
from enumerator interviews, and nonresponse sampling results. 

The proposed ICM operation is a coverage measurement survey that
estimates the true population on Census Day based on interviewing
housing units in a sample of blocks across the country.  It would
involve several main stages:  (1) selecting a sample of blocks in
advance of the 2000 Census that the Bureau would survey after all
census data collection efforts have been completed in those blocks,
(2) developing the best possible address list for ICM sample blocks,
(3) completing interviews for every housing unit in the sample blocks
to compile an independent list of Census Day residents and match this
ICM list to the census list, and (4) using the results to estimate
the true population on Census Day. 

In the first stage, the Bureau would select a sample of blocks from
across the country.  To ensure that this sample was sufficiently
large and representative to accurately estimate coverage errors in
the census for specific geographic areas and population groups, the
Bureau would stratify blocks by characteristics such as the states
they are located in, population size, racial and ethnic composition
of the residents (e.g., blocks in which at least 50 percent of the
residents in the 1990 Census were black), tenure (e.g., whether most
housing units are owned or rented), whether or not the block is in an
urbanized area, and other factors.  Stratifying and weighting the
sample blocks, rather than just drawing a simple random sample of
blocks across the country, would enable the Bureau to include an
adequate number of sample units to provide estimates of census
coverage errors for specific population groups or areas, even if they
constitute a relatively small part of the total population in the
nation. 

Once the ICM sample has been selected, the Bureau would compile an
enhanced master address list for the sample blocks.  This enhanced
address list is intended to be the most complete listing possible of
the housing units in those blocks, given that it would be produced by
more intense and higher quality listing procedures than are possible
for the census as a whole.  The Bureau would create this list by
combining, comparing, and reconciling the address list from the
census with an independent list developed by Bureau enumerators
before the ICM interviews begin. 

In the third stage, Bureau enumerators would complete an interview at
the housing units in the sample blocks after basic census data
collection has been done.  Under its current plan, the Bureau intends
to use computer assisted personal interviewing (CAPI) technology,
laptop computers that have the ICM questionnaire and other data
needed for the interview already preloaded into the machine.  The
Bureau enumerators would attempt to complete an interview for each
housing unit on the enhanced address list, thereby obtaining a roster
of the people living at the unit on Census Day.  Once this ICM roster
was completed, the CAPI system would match all census and ICM
responses possible and reveal the roster from any census
questionnaire for that particular address.  The Bureau enumerator
would then attempt to reconcile any differences between the different
rosters and determine which persons should have been enumerated at
the housing unit according to census residency rules.\6

In the final stage, information from the ICM interviews would be used
to estimate the extent to which housing units and people were
correctly enumerated, missed, or counted in error for the entire
census.  The Bureau would estimate the correct population for entire
geographic areas, as well as for specific poststrata as defined by
characteristics such as age, sex, tenure, race and ethnic origin.  In
other words, while stratification of the original sample would be
done on the basis of the characteristics of blocks,
poststratification would be based on the characteristics of
individuals.  For example, in the Oakland test site of the 1995
Census Test, one ICM poststratum for which the Bureau produced an
estimate was Asian and Pacific Islander females between the ages of
18 and 29 who lived in nonowner (rental) housing units.  The
resulting estimates for all poststrata would be incorporated through
statistical procedures into the final census data. 

To address concerns raised about the PES during the adjustment
decision after the 1990 Census, the Bureau plans several major design
changes for its coverage evaluation survey in the 2000 Census. 
Perhaps most significantly, the Bureau intends to make ICM an
integral part of the census process in 2000, thus producing one
official set of numbers that reflect the Bureau's best estimate,
rather than the original and adjusted census data sets that were
produced after the 1990 Census.  Thus, unlike the process followed in
the 1990 Census adjustment decision, this "one-number census" design
would not include a step where two sets of numbers are evaluated to
determine which set is more accurate:  the data incorporating the
results of the ICM survey would automatically become the official
census data.  This one-number approach may help to mitigate concerns
expressed by the Secretary of Commerce when he decided not to adjust
the 1990 Census, such as the potential for confusion that more than
one set of numbers could create and the potential for political
considerations to play a part in choosing between sets of numbers
when the outcome of the choices (such as differences in apportionment
of seats in Congress) can be known in advance of a decision. 

The Bureau plans other changes that are intended to improve the
timeliness and accuracy of the ICM results, compared with those
produced by the 1990 PES.  The ICM is designed to be completed in a
much shorter time than the PES in order to meet the deadline for
reporting census data for apportionment purposes.  The CAPI
technology is one of the key design changes that can improve
timeliness since it reduces the need for additional follow-up
interviews of sample units.  The Bureau also proposes using a sample
in the 2000 ICM that is approximately five times larger (about
750,000 housing units) than the 1990 PES (about 150,000 units).  This
larger sample should allow the Bureau to produce direct estimates for
each state and improve the quality of estimates for substate
geographic areas.\7 As another enhancement of the 1990 PES
procedures, the Bureau is exploring ways to produce household-level
data.  Persons would be added to or subtracted from individual
housing units through the ICM estimation procedures, thus providing
household characteristic data for researchers and other data users,
in place of using the 1990 PES procedure that would have adjusted
only the block data totals.  As a consequence of these changes,
especially the larger sample size, the planned 2000 ICM is also more
expensive than the 1990 PES (in constant 1990 dollars, the cost is
$230 million for the 2000 ICM compared to $55 million for the 1990
PES).\8


--------------------
\6 Because the ICM procedures estimate the quality of census data
collected by comparing ICM and census results for the same housing
units, the Bureau would use 100-percent follow-up of nonrespondents
in all ICM sample blocks, instead of sampling a portion of the
nonrespondents. 

\7 A direct estimate is based entirely on data from the area for
which the estimate is calculated.  For instance, a direct population
estimate for Missouri would be calculated using only data collected
from Missouri.  Indirect estimates, such as the 1990 PES state
population estimates, draw on data from outside the area being
estimated. 

\8 Even if Congress should decide against using ICM to produce the
final census numbers, some portion of the resources slated for ICM
would still be needed for a smaller coverage survey operation that
would be used for evaluation purposes only.  Such an operation is
essential for evaluating the quality of the census, especially at
subnational levels, and also provides information used to plan and
budget the next census. 


      RESEARCH AND TEST RESULTS
      FOR ICM METHODS HAVE SHOWN
      MIXED RESULTS
------------------------------------------------------- Appendix I:2.3

The Bureau has used a combination of computer simulations and field
testing in its research to design and refine the proposed ICM
operation for the 2000 Census.  Simulations of ICM results using 1990
Census data showed general improvement over the results produced by
the 1990 counting operations.  Bureau simulations also indicated that
an ICM survey of the size proposed for 2000 could support a design
that would achieve for each state a coefficient of variation of
approximately 0.5 percent or a standard error of 60,000 persons,
whichever is smaller.\9 The simulated ICM reduced the patterns of
differential undercounts across population subgroups and areas
observed in the 1990 Census data. 

The Bureau had several key ICM-related objectives in the 1995 Census
Test.  Operational objectives focused on whether the new procedures,
with heavy reliance on CAPI technology, would work and improve the
completeness and timeliness of the coverage survey operation. 
Technical objectives focused on continuing the evaluation of two
potential estimation methods for the ICM, called Dual System
Estimation (DSE) and CensusPlus, as well as completing a number of
studies to evaluate potential sources of bias in the population
estimates produced by ICM. 

Statistical estimation methods are needed to translate the
information from the ICM interviews into estimates of the true
population, which in turn generate the factors used to correct the
raw census counts up through nonresponse follow-up.  For example, if
the estimation method indicates that the census undercounted people
in a particular poststratum by 4 percent, the Bureau would multiply
every person counted by the census in that poststratum by 1.04 to
produce the final census counts.  DSE is a capture-recapture
estimation method that assumes neither the census nor the ICM counts
everyone.  Instead, using probability theory, it uses a comparison of
the results from the two lists (the census and the ICM survey) to
estimate the total population.\10 In other words, it assumes that
using two independent estimates of the population can generate a
third, better estimate of the "true" population.  DSE was used in the
1990 PES and prior census coverage evaluation surveys, as well as
several tests, so the Bureau has a body of research and experience to
rely on in the design and execution of the method.  The other major
advantage of this method is that the resulting estimates include a
component to estimate persons missed by both the census and the ICM
survey.  However, DSE is a complex estimation method.  Therefore, it
takes more time to complete population estimates using DSE, and the
method may be harder to explain to the public.  In contrast,
CensusPlus is a new method that the Bureau had never tested before
1995.  CensusPlus assumes that a second, higher quality survey (the
ICM) can find the "true" population by reconciling an ICM roster with
the census roster for the same housing unit.  The reconciled count
provides a ratio to extrapolate for non-ICM households.  The major
advantages of CensusPlus are that it is simpler than DSE, and may be
faster to complete and easier to explain. 

The results of the 1995 Census Test for ICM were mixed.  Given that
it was the first field test of the operation, this was not
surprising.  Among the successes that the Bureau identified in the
test for ICM was the CAPI-based interviewing, which was well received
by enumerators and those being interviewed, and proved feasible for
use in a coverage survey.  The test results showed that this
technology offers considerable advantages in terms of timeliness,
control, and quality of ICM interview data.  Overall timeliness of
the coverage survey operation was much improved compared with the
1990 PES experience.  The Bureau completed field work for the 1995
ICM in about 2 months less time than it took to complete work for the
1990 PES, which enabled the Bureau to produce the final census data
for both estimation methods before the end of the calendar year. 
Finally, evaluations of specific potential sources of bias in the ICM
estimates and of other data collection errors indicated that the
operations were generally unbiased and effective. 

While some of the new techniques and processes worked well in the
census test, the test results also clearly showed that further
research is needed in a number of areas.  The Bureau experienced some
serious operational and technical problems with the ICM in the 1995
Census Test.  On the operational side, the most serious problems were
a high rate of ICM nonresponse and the failure to load all census
data into the laptop computers in time for the ICM interviews.  The
big technical problem was the poor showing of the CensusPlus
estimation method. 

According to Bureau evaluations, the nonresponse rates for the ICM
interviews were too high, generating more missing data than the
Bureau's estimation methods were designed to handle.  Some of the
nonresponses represented partial interviews that did not provide
sufficient data for the Bureau to use in reconciling census and ICM
rosters (i.e., there was not enough specific information to be able
to tell whether a person listed on the census roster was the same
person as one listed on the ICM roster).  High rates of noninterviews
and missing data can create significant problems for the Bureau when
it attempts to estimate the true population.  The population
estimates can vary depending on different assumptions the Bureau
makes about how to treat the missing information.  For example, in
the Bureau's evaluation of coverage in the 1980 Census, different
assumptions about the treatment of missing data, along with other
limitations, generated 12 different sets of estimates of the true
population.  In the 1995 Census Test, the Bureau imputed responses
for missing data based on the responses that it was able to obtain,
but its subsequent evaluations of the test indicated that the ICM
nonrespondents were dissimilar to the ICM respondents. 

Although the ICM began after nonresponse follow-up ended, the Bureau
had not yet finished recording all the data from the last nonresponse
interviews.  Therefore, not all the census data needed for ICM
interviews were loaded into the laptop computers before enumerators
went out for those interviews.  Bureau officials said that this
problem was compounded because a relatively large portion of the
census data from nonresponse follow-up interviews came in at the end
of that operation.  Census data were missing in 29 percent of the ICM
sample cases from which interviewers called up information.  For
those cases, this made on-the-spot reconciliation of ICM and census
rosters impossible and also eliminated the possibility of ICM
interviewers probing to resolve discrepancies and identify persons
not originally accounted for.  Among other difficulties with the
computer technology, the Bureau discovered problems with the flow and
complexity of the survey instrument loaded into the machines. 

Of the two estimation methods the Bureau tested in 1995, only DSE
showed a consistent ability to reduce the differential undercount of
traditionally undercounted population groups.  In contrast, the
CensusPlus method produced an unexpectedly poor showing according to
Bureau officials.  The estimates produced by this method were lower
than the total count after nonresponse follow-up (i.e., from all
phases before ICM results were incorporated) for some traditionally
undercounted population groups.  CensusPlus results did not reduce
the differential undercount of blacks and only provided limited
improvement in the counts for Hispanics.  The CensusPlus results also
showed patterns that did not appear reasonable when compared with
independent estimates, such as those produced by demographic
analysis.  Bureau officials were not certain whether the poor
performance of CensusPlus was due to problems with operations and the
computer survey instrument or to flaws in the method itself.  Because
the Bureau has extensive experience with the DSE method, and because
that method has been performing well in recent tests, the Bureau
decided in March 1997 that it will use DSE as part of the ICM
procedures planned for the 2000 Census. 

The Bureau began testing redesigned procedures and computerized
survey instruments for ICM in its 1996 Community Census, for which
the ICM survey portion started in January 1997.  Among the planned
changes were revisions to the computerized survey instrument to make
it easier for respondents and interviewers to move through the
questions.  Also, the ICM schedule was extended by about 2 weeks to
allow the Bureau to load all census data on the laptop computers
before ICM interviews.  The Bureau also intended to use the longer
schedule to implement a special operation to try to convert ICM
noninterviews into completed interviews, thus alleviating some of the
missing data problems experienced in the 1995 Census Test.  A similar
nonresponse conversion operation for the 1990 PES reduced the
noninterview rates to about 1.5 percent.  The 1996 test should
provide information to determine whether the operational problems
have been addressed sufficiently, but the evaluations from the 1996
Community Census are not expected to be completed until fall 1997. 


--------------------
\9 The standard error (SE) and coefficient of variation (CV) are
measures of the precision of an estimate.  Whatever true value the
estimate might have, the standard error tells how wide an interval to
expect from all possible samples like the one under consideration. 
The CV is the standard error relative to the size of the estimate. 

\10 For a more detailed description of the DSE method and the
mathematical procedures used, see 1990 Census Adjustment:  Estimating
Census Accuracy--A Complex Task (GAO/GGD-91-42, Mar.  11, 1991). 


   COMBINED EFFECTS OF SAMPLING
   FOR NONRESPONSE AND ICM
--------------------------------------------------------- Appendix I:3

The effects of the proposed new statistical methods on the success of
census operations and the quality of the resulting data need to be
viewed in combination.  The Bureau's research to date illustrates
that there are many trade-offs and interrelationships between the
components of alternative census designs.  Sampling a portion of the
nonresponse workload can save time and money compared to attempting
to follow up 100 percent of the nonrespondents, but it is not likely
to significantly improve census accuracy.  The ICM is designed to
address problems with census accuracy, but it is unlikely to be
successful unless preceding data collection efforts, in particular
nonresponse follow-up, are completed on schedule.  The results from
Bureau research suggest that the statistical methods proposed by the
Bureau for 2000 should reduce the bias observed in past census data
(i.e., the differential undercounts), but these methods would also
introduce additional random error in the data because of sampling. 
Similarly, designs that do not include sampling for nonresponse
follow-up or ICM also involve trade-offs.  For example, such designs
would be easier to explain to the public and more closely resemble
past censuses.  They would not introduce the additional level of
uncertainty in the results that accompanies sampling.  However, the
Bureau's research results and projections also suggest that those
designs would be more expensive and show no likelihood of reversing
or substantially reducing accuracy problems in census data. 

Projections of the expected accuracy, equity, costs, and operational
feasibility of alternative census designs are likely to change as the
Bureau's research continues.  The Bureau and other census observers
have identified a number of areas in which additional research and
decisions are needed with regard to the details of the proposed
statistical methods.  Such research is particularly critical because
technical changes and refinements can affect census results. 


      RESULTS FROM COMPUTER
      SIMULATIONS ILLUSTRATE
      TRADE-OFFS IN ACCURACY
------------------------------------------------------- Appendix I:3.1

To determine the potential levels and sources of error for various
levels of geography, the Bureau relied primarily on computer
simulations.  At our request, the Bureau provided us data from its
most recent simulations of the results that would likely be produced
in the 2000 Census using various alternative census designs. 
According to Bureau officials, one important advance in this
research, compared to previous simulations, was that they were able
to use detailed information from the operational data files of the
1990 Census about the processing of census forms collected from the
nation's housing units.  For simulating the results of sampling for
nonresponse follow-up, the most important operational items were the
response status (i.e., whether or not a given unit responded to the
census by mail) and the check-in date of each census form (which
identified when the Bureau was able to collect data for each unit). 
Using this information, the Bureau was able to identify nonresponding
housing units and define the nonresponse follow-up sampling universes
for different designs with a high degree of accuracy, yielding more
realistic results with fewer assumptions than were needed for
previous simulations.  To account for expected growth in the
population, the Bureau used population projections for the counts and
characteristics of persons in 2000.  In addition, the Bureau assumed
in its simulations that the percentage undercounts (and overcounts)
measured for population groups by the 1990 PES would also apply in
the 2000 Census. 

The Bureau's summary chart showing projected results from its
simulations of alternative designs for conducting the 2000 Census, as
of June 1997, is presented in appendix II.  Because of the
limitations of this research, the Bureau's estimates should serve
only as a rough illustration of possible results in 2000.  The most
important limitation is that actual results can vary from the
expected results produced in theory or in a computer simulation. 
Among other limitations are that (1) the Bureau continues to refine
the different methods it is studying; (2) as new information becomes
available, such as data on expected staffing and pay levels in 2000,
the results may vary; and (3) more research is needed to better
understand and quantify some of the effects and sources of error that
are not reflected in this current set of results.\11

Despite these caveats, the simulation results suggest that, relative
to the size of the population being estimated, the new methods
proposed by the Bureau would generally reduce the level of error in
census data for the nation, states, congressional districts, and most
census tracts.  Results near the levels projected by the Bureau's
simulations for its refined plan would represent a reduction in the
relative error levels experienced in the 1990 Census, as well as in
the levels projected for a 2000 Census design that incorporates all
proposed improvements in 1990 Census procedures except those
involving sampling or statistical estimation. 

The Bureau's simulation results for alternative designs also
illustrate one of the major trade-offs in accuracy between designs
that use sampling and statistical estimation and those that do not. 
While the data showed that most places and geographic levels had
lower rates of error using the methods the Bureau proposes to use in
2000, some places had lower rates of error using conventional census
methods without sampling and statistical estimation.  The simulation
data suggest that the Bureau's current design for the 2000 Census
would likely produce results that appear more accurate or more
equitable by at least three broad criteria:  (1) the average levels
of error are better; (2) the shape of the error distributions is
compressed closer to the average levels; and (3) the cumulative error
distributions also appear to be better.  For example, the difference
between the average relative error rates for the Bureau's current
design for the 2000 Census and a conventional design without sampling
range from 0.8 percent at the level of census tracts (1.1 percent
compared to 1.9 percent) to 1.8 percent for the national total (0.1
percent compared to 1.9 percent).  The distribution of tracts, using
the Bureau's current design, showed that over 90 percent of tracts
had results between 0.5 percent and 2.0 percent relative error; the
comparable range to account for 90 percent of tracts using
conventional procedures would extend from under 0.5 percent to
between 4.0 and 4.5 percent.  In terms of the cumulative
distributions, while the data again indicated that over 90 percent of
tracts had error rates of less than 2.0 percent using the Bureau's
current design, only about 63 percent of tracts had rates of less
than 2.0 percent using the conventional procedures. 

However, the results also show that some places that should have very
low error rates using a conventional census design could have higher
error levels if sampling for nonresponse and ICM are used.  For
example, the Bureau's current plan for the 2000 Census is designed to
achieve a relative error rate of 0.5 percent for all but the largest
states.\12 But its simulations projected that two states could have
error rates of less than 0.5 percent by using a conventional design
without sampling in the 2000 Census.  (In the 1990 Census, five
states had estimated error rates of under 0.5 percent.) The trade-off
is more noticeable for smaller geographic areas.  The smallest
geographic areas for which we have detailed data from the Bureau
simulation are census tracts.\13 Using a trimmed data set, the Bureau
calculated that its current plan for 2000 (using direct sampling for
nonresponse follow-up, together with ICM) would produce less error
for 64 percent of census tracts.\14 The time-truncation option
produced less error for 54 percent of tracts, and the 90-percent
truncation option produced less error for only 51 percent of tracts. 
The converse of these figures is that the 1990 Census procedures
performed better for approximately 40 to 50 percent of tracts,
depending on the option used for comparison. 

The question therefore becomes, how much better or worse are the
error levels for individual tracts using different designs?  The
Bureau is still working with and studying the data set from its
latest simulations and has not yet produced detailed data tables to
address that question directly.  But it did provide us with data from
its simulation showing the distribution of census tracts by the level
of relative error.  Table I.1 provides summary information on the
distribution of census tracts by the level of relative error.  For
this table, we chose to present data for all 60,128 tracts from the
untrimmed data set.  We used the untrimmed data set because we
believe that the ends of the distributions, which the Bureau trimmed
from the other data set, matter unless the Bureau decides not to
apply the same methods to these tracts. 



                                    Table I.1
                     
                         Distribution of Census Tracts by
                      Relative Error Level Using Alternative
                                  Census Designs

                               Relative error level in percentage
                ----------------------------------------------------------------
                       0.5   1.0   1.5   2.0   2.5   3.0   3.5   4.0   4.5
Design             <    to    to    to    to    to    to    to    to    to    />
alternative      0.5   1.0   1.5   2.0   2.5   3.0   3.5   4.0   4.5   5.0   5.0
--------------  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----  ----
Percentage of tracts
--------------------------------------------------------------------------------
Direct           1.5  39.5  41.6  11.6   3.3   1.1   0.5   0.2   0.1   0.1   0.4
 sampling
90-percent       1.5   8.2  40.8  32.9  10.7   3.4   1.3   0.5   0.2   0.2   0.4
 truncation
Time             1.5  16.1  46.7  25.0   6.7   2.1   0.8   0.3   0.2   0.1   0.4
 truncation
No sampling     22.2  12.1  15.0  13.1   8.8   6.6   5.1   4.0   3.5   2.7   6.8

Cumulative percentage of tracts
--------------------------------------------------------------------------------
Direct           1.5  41.0  82.6  94.2  97.5  98.7  99.2  99.4  99.5  99.6  100.
 sampling                                                                      0
90-percent       1.5   9.7  50.5  83.4  94.0  97.4  98.7  99.2  99.4  99.6  100.
 truncation                                                                    0
Time             1.5  17.6  64.4  89.3  96.1  98.2  98.9  99.3  99.5  99.6  100.
 truncation                                                                    0
No sampling     22.2  34.3  49.4  62.5  71.3  77.9  82.9  87.0  90.4  93.2  100.
                                                                               0
--------------------------------------------------------------------------------
Note 1:  Data presented reflect simulation results for 60,128 census
tracts. 

Note 2:  Relative error for the direct sampling, 90-percent
truncation, and time-truncation design alternatives is the combined
sampling error from sampling for nonresponse follow-up and ICM in
simulations of the 2000 Census.  It does not include possible errors
from other sources, such as any bias in the statistical models used
to produce the tract-level estimates. 

Note 3:  Relative error for the no sampling design alternative (i.e.,
without using sampling for nonresponse follow-up or ICM) is the
absolute value of the estimated undercount or overcount rate for
tracts in simulations of the 2000 Census.  It does not include
possible errors from other sources.  Also, although model error would
not apply in the actual use of the no sampling design, it does
represent an unmeasured error component in producing these
tract-level estimates. 

Note 4:  Cumulative percentages may be affected by rounding. 

Source:  Bureau of the Census

There is a clear difference in the shape of the distributions for the
design alternatives using sampling for nonresponse and ICM, and the
distribution for a design that does not use those procedures.  The
distributions of tract data for designs using these new methods are
compressed toward the average relative error level for tracts.  The
distribution of tracts for the conventional census design, while
showing that about 22 percent of all tracts had minimal net
undercounts (i.e., less than 0.5 percent), is more dispersed across
the range of error levels.  This suggests that the tracts that would
have relatively more error using the new methods may have only
slightly more error. 

Figure I.2 illustrates the different distributions of census tracts
by the relative error level produced by the Bureau's selected design
for Census 2000 (the direct sampling option for nonresponse follow-up
together with ICM) and a census design that does not include sampling
for nonresponse follow-up and ICM.  The patterns are similar when the
results for the 90-percent truncation and time-truncation designs are
graphed.  Again, the distributions are compressed toward the average
error level.  However, since the averages for those designs are
slightly higher than for direct sampling, the trade-off compared to a
conventional design is more pronounced. 

   Figure I.2:  Distribution of
   Census Tracts by Error Level
   Shows Trade-Off Between Direct
   Sampling and No Sampling
   Designs

   (See figure in printed
   edition.)

Note 1:  Data presented reflect simulation results for 60,128 census
tracts. 

Note 2:  Relative error for the direct sampling design is the
combined sampling error from sampling for nonresponse follow-up and
ICM in simulations of the 2000 Census.  It does not include possible
errors from other sources, such as any bias in the statistical models
used to produce the tract-level estimates. 

Note 3:  Relative error for the no sampling design (i.e., without
using sampling for nonresponse follow-up or ICM) is the absolute
value of the estimated undercount or overcount rate for tracts in
simulations of the 2000 Census.  It does not include other possible
errors. 

Source:  Bureau of the Census data. 

The Bureau's research over the past several years also showed that,
while both sampling for nonresponse follow-up and ICM procedures
introduce sampling error into census data, they do so in different
proportions at different geographic levels.  Bureau officials found
that, on average, sampling for nonresponse follow-up would contribute
most of the sampling error or variability for smaller geographic
areas, such as tracts and blocks, while ICM would contribute almost
all of the error at the level of congressional districts and larger
geographic areas.  In general, relative sampling error increases as
the population of a geographic area decreases.  Simulation results
also showed that sampling errors could be significantly high for some
very small areas or population groups, although the level of
nonsampling errors for such areas and groups can also be high when
conventional counting methods are used.  This highlights the need for
additional research to identify the block-level effects of different
census designs.  However, relative variability becomes smaller as
block-level data are aggregated to larger geographic areas, and the
simulations indicated that data for areas or groups of equivalent
population size are likely to have similar levels of sampling
variability. 

In large part, the accuracy trade-off in the Bureau's proposed
approach may entail accepting that sampling and statistical
estimation would introduce random sampling error in the data,
especially for small geographic areas (such as most blocks and census
tracts with 1,000 or fewer persons), but would reduce systematic bias
in the results for all larger geographic areas.  Bias in this context
occurs because certain individuals and households are more likely to
be missed by the census.  To the extent that these missed units have
distinctive characteristics, the resulting census data will be biased
since these units are not included in the census tabulations.  Random
sampling error refers to the fact that one random sample will differ
somewhat from another even if the two samples are drawn from the
population in the same random way.  The magnitude of random sampling
errors can be estimated from an actual sample, and it is possible to
limit the magnitude of random sampling errors as part of the sample
design process. 


--------------------
\11 For example, the procedures used to model population estimates
for all smaller geographic areas, such as tracts, using a limited
amount of sample data also generate errors.  The potential magnitude
of those errors and the validity of the assumptions used in the
models are the subjects of research both within and outside the
Bureau. 

\12 For the four states with a population of over 12 million persons
(California, Florida, New York, and Texas), the Bureau's plan was
designed to ensure that the standard errors from sampling did not
exceed 60,000 persons, which produced relative error rates of under
0.5 percent for those states. 

\13 The simulation did not produce block-level data on the potential
effects of the Bureau's current plan and options, but Bureau
officials told us they intend to contract for a study of the effects
on block data. 

\14 The Bureau "trimmed" the number of census tracts represented in
these calculations by removing tracts with unusual characteristics
(e.g., those with especially small or large populations).  Trimming
reduced the number of tracts from 60,128 to 56,022.  A more detailed
explanation of trimming is included in the Bureau's footnotes to its
summary chart in appendix II. 


      BUREAU'S COST PROJECTIONS
      SHOW COST SAVINGS ARE
      POSSIBLE USING ITS CURRENT
      DESIGN FOR CENSUS 2000
------------------------------------------------------- Appendix I:3.2

The Bureau has been conducting research to estimate the overall
effects of using alternative designs on the cost of the 2000 Census. 
To develop cost projections for the full census cycle, the Bureau
used two cost models, one to generate estimates for Bureau
headquarters activities and the second, called the Year 2000 Cost
Model, to generate expected costs in all nonheadquarters components
of the census cycle for fiscal years 1997-2001, using information
from the 1990 Census and research for the 2000 Census.  Among the
underlying design principles of the Year 2000 Cost Model are that it
is intended to replicate the whole census process and model
interrelationships among operations and activities.  For example, if
the assumed response rate changes, a domino effect may result for
many activities and costs, in areas as diverse as recruiting and
training of census enumerators, printing, and postage.  The Bureau
contracted with an outside consultant to provide validation of the
Year 2000 Cost Model's logic.  The firm, Booz-Allen & Hamilton, Inc.,
was responsible for writing an executive summary explaining how the
model operates and detailing sources of model inputs. 

Assuming the Bureau can obtain an overall mail response rate of about
67 percent, it estimated in June 1997 that the cost for the entire
2000 Census cycle would range from about $4.0 billion to $4.8 billion
(in 2000 dollars) for different designs.  Given the cost estimates
provided to us by the Bureau, its selected design, which would use
the direct sampling option for nonresponse follow-up, appears to
offer the greatest potential to control the overall cost of the 2000
Census.  According to the Bureau's estimates, the difference between
its current selected design and a plan that would not use sampling
for nonresponse or ICM to produce the final counts would be about
$700 million to $800 million. 

Cost projections for all designs may increase depending on changes in
a number of cost-model assumptions, such as the pay and turnover
rates that affect staffing costs and the size of the nonresponse
workload.  The Bureau was still examining and validating wage rate
information from a study by Westat, Inc., when we completed our work. 
That study recommended higher wage rates to ensure an adequate labor
supply in the 2000 Census, but the Bureau has not included those
rates in its current cost estimates.  Costs are also likely to
increase if the Bureau cannot fully implement all of the proposed
changes in operations for the 2000 Census as planned.  For example,
the Bureau may need to rely more heavily on labor-intensive clerical
procedures than what is now reflected in the cost-model estimates if
new technology does not work as well as planned.  Costs would also
escalate if the efforts planned to encourage mail responses to the
census do not increase response rates as much as the Bureau
anticipates, resulting in a larger nonresponse workload than the
Bureau has been projecting for the 2000 Census. 


      ADDITIONAL RESEARCH,
      TESTING, AND CLARIFICATION
      OF OBJECTIVES REMAIN TO BE
      COMPLETED BEFORE THE 2000
      CENSUS
------------------------------------------------------- Appendix I:3.3

There is still uncertainty surrounding the potential results that
would be produced by alternative census designs and methods and
questions that need to be answered.  In the relatively short time
available before the next census, the Bureau has identified
additional research and testing that it needs to complete in order to
refine its plans, as well as to address broader concerns expressed by
some Members of Congress and other observers about the Bureau's
proposal to expand the use of statistical methods.  The remaining
work to prepare for Census 2000 also includes reaching decisions on
some technical details of the proposed methods that can affect the
final results. 

Bureau officials have been developing a prioritized list of research
topics on sampling and estimation methods in the census that need
further work.  For example, the design and selection of the ICM
sample (i.e., identifying the number and types of blocks that would
be surveyed in areas across the country) would need to be determined
on the basis of the desired level of precision in estimates for
various levels of geography and population groups.  The Bureau also
plans to continue research to refine the overall estimation methods
and procedural details for producing a census data file.  One of the
Bureau's goals for this research is to develop a way to take the
results from the proposed estimation methods and place persons down
to the level of individual housing units in each block.  Another key
research topic is determining when and how to produce direct and
indirect population estimates.  Evaluations of the 1995 Census Test
also indicated the need for more development of the procedures and
software used for computerized matching of addresses and individuals
listed by the ICM and the other census operations.  These are only
some of the remaining topics for investigation that Bureau
researchers identified. 

Issues that have been raised in Congress and by observers of the
census planning process, including members of the statistical
community, concerning the expanded use of statistical methods in the
2000 Census also pose important questions for the Bureau's research
efforts.  These issues generally can be grouped into two areas.  The
first area involves questions about the technical soundness of the
proposed methods, such as whether the underlying assumptions are
valid, the proposed methods are statistically robust (i.e., that the
results produced are not overly sensitive to variations in reasonable
assumptions and alternatives to the production procedures), and the
effects and consequences of using and combining these methods are
well understood.  For example, one important question in weighing the
effects of alternative designs is the extent to which the Bureau's
estimates for the precision of population estimates produced by
various methods accurately account for all sources of error.  The
second set of issues involves questions about the operational
feasibility of the proposed procedures.  Because the sample surveys
that the Bureau intends to employ in 2000 are large and complex, some
observers are concerned about whether all components of the Bureau's
plan can be implemented effectively and with limited errors in a
decennial census environment.  One reason for such concerns is that,
several months after the July 1991 census adjustment decision, the
Bureau discovered a computer coding error in the 1990 PES estimation
procedures.  Correcting for that error, together with other
subsequent modifications and edits, lowered the PES estimates of the
1990 net undercount by about half a percentage point, from around 2.1
percent to about 1.6 percent.  The Bureau should be better able to
address both sets of issues as it completes more research in the
priority areas it has identified and undertakes evaluations of how
the proposed statistical methods performed in the 1996 Community
Census and in the Census 2000 Dress Rehearsal in 1998. 

The work that remains to be done by the Bureau is important because
decisions about the details of its methods and procedures can affect
the census results.  Some of these technical details involve policy
decisions, such as defining what sample allocation is equitable or
what level of precision the Bureau's methods should attempt to
achieve for different levels of census geography.  One of the most
difficult challenges regarding the design of census-taking procedures
is that the formula for apportioning seats in the House of
Representatives is mathematically very sensitive to small changes in
the number of people in states that receive the last few seats. 
Variations and errors in conventional census data collection can also
affect apportionment; this is not a problem unique to the use of
statistical methods.  With the current apportionment formula and size
of the House of Representatives, a perfect count or apportionment is
not likely using any census design, as demonstrated in some of the
Bureau's research.  The question is which design will produce better
estimates of the population. 

When Secretary of Commerce Robert Mosbacher made his decision not to
adjust the 1990 Census using the results of the PES, he recognized
this dilemma and noted that some sensitivity should be expected.  He
pointed out that no production of the complexity of the census could
be completely prespecified and that technical decisions were made in
the course of the estimation procedure following the 1990 Census. 
However, in commenting on the precedent for future censuses, the
Secretary also noted that there are different implications to the
many decisions that are made during the course of the census process
(when "the decision maker does not know the import of his decision")
and the decisions made when the results of different choices can be
known.  The House Committee on Government Reform and Oversight raised
similar concerns about the potential subjectivity of sampling and
statistical estimation methods in its report released on September
24, 1996.  To mitigate such concerns about the subjectivity of its
proposed statistical methods in the 2000 Census, the Bureau expects
to subject its plans and procedures for implementing the methods to
the review and scrutiny of professional experts, advisory committees,
and other stakeholders.  According to the Bureau, once the detailed
procedures for the statistical methods have been developed by the
Bureau and accepted by the reviewers, these procedures will be
"frozen" to ensure that there is no introduction of subjectivity into
the results for Census 2000. 


BUREAU OF THE CENSUS SUMMARY
INFORMATION ON DESIGN ALTERNATIVES
FOR THE 2000 CENSUS
========================================================== Appendix II

The Bureau's summary data and information on alternative designs for
conducting the 2000 Census, as of June 1997, are presented in this
appendix.  Figure II.1 shows the projected error rates from the
Bureau's simulations for selected design alternatives, together with
cost estimates for those designs and other explanatory information in
the accompanying footnotes. 

Please note that, while we chose to present data in appendix I from
an "untrimmed" data set of simulation results for all 60,128 census
tracts, the Bureau used the "trimmed" set of results for 56,022
tracts in its chart to reduce the potential for unusual tracts to
affect the results.  The Bureau's use of trimming, along with other
details on the methods and assumptions used to produce the chart
data, is discussed in the footnotes.  In general, close attention to
the Bureau's footnotes is important for understanding the information
presented in the chart and the limitations of the Bureau's data. 

We made some minor formatting changes needed to reproduce the
Bureau's chart in our report and added a figure title and source. 
Otherwise, the following material in this appendix presents the
Bureau's original text, data, and notes. 



                                                                                      Table II.1
                                                                       
                                                                         Bureau of the Census Summary Data on
                                                                       Projected Costs and Accuracy of Selected
                                                                        Census 2000 Alternative Methodologies

                                           NATIONAL              STATES (excluding DC)        CONGRESSIONAL DISTRICTS              CENSUS TRACTS
                                   -------------------------  ---------------------------  ------------------------------  ------------------------------
                                      Error, by source\b          Error, by source\b             Error, by source\b        Error (trimmed), by source\b,c
                                   -------------------------  ---------------------------  ------------------------------  ------------------------------
                          Cost in  Misses                                                  Misses
THE CENSUS BUREAU'S          2000       /                     Misses/                           /                          Misses/
PLAN AND ALTERNATIVE      dollars  Double                      Double                      Double                           Double
METHODOLOGIES FOR        (billion  Counts  Sampli   Combined  Counts\  Sampli    Combined  Counts  Sampling      Combined  Counts\               Combined
CONDUCTING CENSUS 2000       s)\a      \d      ng    Error\e        d      ng     Error\e      \d        \f       Error\e        d  Sampling      Error\e      Comments
-----------------------  --------  ------  ------  ---------  -------  ------  ----------  ------  --------  ------------  -------  --------  -----------  --  ----------------------
THE PLAN TO ASSURE MEETING IMPROVED ACCURAC
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Refined Plan:                $4.0       *    0.1%       0.1%        *              0.5%\g     * 2    0.6%\h        0.6%\h        *    1.1%\h       1.1%\h      -Low combined error
 -Direct Sampling for                                                  0.5%\g                                                                                   for small geographic
 NRFU                                                                            (0.2% to             (0.3%      (0.3% to              (0.6%     (0.6% to       areas
 -Census Tract Response                                                 (0.2%     0.5%)\g                to       2.3%)\i                 to    2.4%)\c,i
 Control                                                                   to                        .3%)\i                         2.4%)\c,
 -Quality Check                                                        0.5%)\                                                              i
                                                                            g

ALTERNATIVES THAT DO NOT MEET IMPROVED ACCURACY AND/OR REDUCED COST GOALS OF CENSUS 2000
(Improved forms/multiple mail contacts/paid advertising strategy yielding about 67 percent mail response rate)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Conduct Census 2000          $4.7    1.9%     N/A     1.9%\d     1.9%     N/A      1.9%\d    1.9%       N/A        1.9%\d     1.9%       N/A       1.9%\d      -Much higher cost than
 Using Improved                to                                                                                                                               the Refined Plan
 Procedures\j            $4.8\k,l                               (0.4%            (0.4% to      (-               (-1.2% to   (-1.2%              (-1.2% to       -Higher combined
 Except there is:                                                  to             3.2%)\i    1.2%                 7.0%)\i       to              6.2%)\c,i       error for all
 -Full NRFU (no                                               3.2%)\j                          to                          6.2%)\c                              geographic areas
 sampling)                                                                                 7.0%)\                               ,i                              -A PES is used to
 -No Quality Check\k                                                                            i                                                               evaluate census
 -An Evaluation Study +                                                                                                                                         quality; results
                                                                                                                                                                available after
                                                                                                                                                                delivery of
                                                                                                                                                                apportionment totals
                                                                                                                                                                -Increased activities
                                                                                                                                                                (publicity, followup
                                                                                                                                                                visits at all
                                                                                                                                                                vacant housing units,
                                                                                                                                                                etc.) to attempt to
                                                                                                                                                                achieve census
                                                                                                                                                                coverage consistent
                                                                                                                                                                with 1990 levels
Conduct Census 2000        $4.4\l       *    0.1%       0.1%        *              0.5%\g     * (    0.6%\h        0.6%\h        *    0.8%\h       0.8%\h      -Higher cost than the
 Using Improved                                                        0.5%\g                                                                                   Refined Plan
 Procedures                                                                      (0.2% to           0.3% to      (0.3% to              (0.4%     (0,4% to       -Low combined error
 Except there is:                                                       (0.2%     0.5%)\g           2.3%)\i       2.3%)\i                 to    1.9%)\c,i       for small geographic
 -Full NRFU (no                                                            to                                                       1.9%)\c,                    areas
 sampling)                                                             0.5%)\                                                              i                    -Increased risk of
 (Still includes the                                                        g                                                                                   management failure
 Quality Check)

SCENARIO SHOWN FOR REFERENCE AND COMPARISON ONLY; THIS IS NOT AN ALTERNATIVE FOR CENSUS 2000\m
(1990 forms/single mail contact/pro bono advertising strategy yielding about 55 percent mail response rate)

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Conduct Census 2000      $4.8\k,n    1.9%     N/A     1.9%\d     1.9%     N/A      1.9%\d    1.9%       N/A        1.9%\d   1.9%\d     N/A (       1.9%\d      -Much higher cost than
 Using 1990                                                                                                                                                     the Refined Plan
 Procedures\j                                                   (0.4%            (0.4% to      (-               (-1.2% to   (-1.2%               -1.2% to       -Much higher combined
 -Full NRFU (no                                                    to             3.2%)\i    1.2%                 7.0%)\i       to             6.2%) \c,i       error for all
 sampling)                                                    3.2%)\i                          to                          6.2%)\c                              geographic areas
 -No Quality Check\k                                                                       7.0%)\                               ,i                              -A PES is used to
 -PES                                                                                           i                                                               evaluate census
                                                                                                                                                                quality; results
                                                                                                                                                                available after
                                                                                                                                                                delivery of
                                                                                                                                                                apportionment totals

DISCARDED ALTERNATIVES THAT MEET IMPROVED ACCURACY AND REDUCED COST GOALS OF CENSUS 2000
(Improved forms/multiple mail contacts/paid advertising strategy yielding about 67 percent mail response rate)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
The Original Plan:         $4.2\o       *    0.1%       0.1%        *              0.5%\g     * (    0.6%\h        0.6%\h        *    1.5%\h       1.5%\h
 Truncate at 90%                                                       0.5%\g
 -Census Tract Response                                                          (0.2% to           0.3% to       0.3% to              (0.8%     (0.8% to
 Control                                                                (0.2%     0.5%)\g           2.3%)\i       2.3%)\i                 to    2.9%)\c,i
 -Sampling for NRFU                                                        to                             (                         2.9%)\c,
 -Quality Check                                                        0.5%)\                                                              i
                                                                            g
Implementation             $4.6\o       *    0.1%       0.1%        *              0.5%\g       *    0.6%\h        0.6%\h        *    1.3%\h       1.3%\h
 Alternative 1: Time                                                   0.5%\g
 Truncation                                                                      (0.2% to             (0.3%       0.3% to              (0.7%     (0.7% to
 -Census Tract Response                                                 (0.2%     0.5%)\g                to       2.3%)\i                 to    2.7%)\c,i
 Control                                                                   to                       2.3%)\i                         2.7%)\c,
 -Sampling for NRFU                                                    0.5%)\                             (                                i
 -Quality Check                                                             g
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


Legend:
* -Too small to measure with reasonable cost and operations
NRFU -Nonresponse Followup
Quality Check -Also known as the Integrated Coverage Measurement
Survey or ICM
N/A -Not applicable; in the absence of any sampling process, there is
no sampling error
+ -The evaluation study would yield coverage measures similar to the
1990 PES;
results not available until after delivery of the apportionment
totals
PES -Post Enumeration Survey; results not available until after
delivery of the
apportionment totals

\a The dollar figures shown do not include the higher wage rates
recommended by Westat, Inc.  to ensure an adequate labor supply for
Census 2000.  The results of the Westat study are still being
evaluated by the Census Bureau for their effect on the cost of the
Refined Plan and each alternative to the plan for Census 2000.  For
the Refined Plan and Alternatives 5 and 6 that use sampling to reduce
the workload for nonresponse followup, the effect is likely to be
less than $100 million.  For the alternatives that include full
(rather than sample) nonresponse followup operations, the nearly 60
percent (11.9 million housing unit) increase in workload, multiplied
by the recommended wage rates, could add several hundred million
dollars to the estimated cost figure shown. 

\b All error figures were derived using simulations of 1990 census
estimates of undercounts and overcounts for census tracts.  To
account for expected growth in the population of the United States
through the year 2000, the 1990 census tract population totals by
race and Hispanic origin were projected using the factors shown on
Attachment 1.  The projection factors were derived from a widely used
process known as Demographic Analysis.  The simulations assume that
the percentage undercounts (and overcounts) measured for each group
in the 1990 Post Enumeration Survey also would apply in Census 2000. 
To determine the amount of undercount or overcount for each census
tract, the projected population totals for each were computed with
and without the results of the 1990 PES for each region and for the
various segments of the population within it. 

The totals for the specific census tracts in each geographic entity
were summed to derive the error rates for the more populous
geographic levels shown on this chart, such as congressional
districts, states, and the Nation. 

\c The average census tract has a resident population of about 4,000
people; however, some census tracts have very few people and some are
far more populous because of specific local circumstances and changes
in settlement pattern since the census tracts initially were
established.  To evaluate the effect of sampling on all except the
most unusual census tracts, the error distributions shown were
ï¿½trimmedï¿½ (a widely used practice in analyzing large data sets) by
removing values for census tracts that contain only group quarters
population, census tracts that contain 10 or fewer people, the least
populous 3 percent of all remaining census tracts, and the most
populous 3 percent of all remaining census tracts.  Trimming was done
separately for each alternative shown. 

\d The single figure shown in the ï¿½Misses/Double Countsï¿½ column is
the estimated net undercount rate.  In 1990, this rate was 1.6
percent, meaning that the 1990 census population total for the United
States failed to include more than 4 million people.  The estimated
net undercount rate in 2000 is projected to be 1.9 percent if there
is no Quality Check operation.  This estimate is based on growth
rates in the populations most difficult to count; this means Census
2000 likely will fail to include more than 5.2 million people. 

The net undercount figure fails to convey the magnitude of
enumeration errors actually made during a decennial census.  Several
studies looked at the component measures of ï¿½grossï¿½ undercount --
total people missed and total erroneous enumerations.  There is no
generally accepted definition of gross undercount, and different
studies had widely divergent totals for people missed and people
included erroneously.  Regardless of the components included in the
different measures, the net undercount -- people missed minus people
included erroneously -- was about 4 million people. 

\e The ï¿½Combined Errorï¿½ figures for congressional districts and
census tracts do not include error due to modeling; model error would
not apply to either of the nonsampling alternatives. 

\f One might expect the ï¿½Sampling Errorï¿½ figures for a congressional
district always to be larger than the sampling error figures for a
state.  However, some congressional districts are more populous than
the least populous states. 

\g To ensure highly accurate population totals for each state
(because these totals are used to apportion the 435 seats in the U.S. 
House of Representatives among the 50 states) the Census Bureau has
designated the sampling processes to yield a ï¿½coefficient of
variationï¿½ of 0.5 percent.  To control the ï¿½standard errorï¿½ (the
expected amount of variation in the number of people that could be
included in each state's total) the designed coefficient of variation
will actually be smaller than 0.5 percent in the four states that had
a 1990 census population of 12 million or more (Texas, New York,
Florida, and California); the figures in parenthesis show the range
in variation. 

\h The single figure shown is the ï¿½average errorï¿½ (the numeric mean)
of the estimated error for each individual entity (all congressional
districts or all census tracts) in this geographic level. 

\i The figures in parenthesis show the ï¿½range of errorï¿½ (lowest and
highest situations) for all entities in this geographic level. 
Negative figures identify overcount estimates; overcounts happen for
several reasons, including erroneous inclusion of some people on
completed census forms.  All other figures identify undercount
estimates; undercounts happen when residents of an area are not
included on any census form. 

\j This scenario restores several coverage improvement activities as
a substitute for the "Quality Check" planned for Census 2000.  These
activities have been viewed by the National Academy of Sciences, the
Inspector General for the Department of Commerce, and many others as
only marginally effective.  However, they are the only alternatives
expected to deal with some aspects of the total undercount and the
differential participation rates among some segments of the
population. 

\k An obvious question is, ï¿½Why should the Congress pay for the
improvements (other than sampling) offered by the plan for Census
2000 when the cost is nearly as high as repeating 1990 census methods
and the quality appears no better?ï¿½ The answer starts with
understanding that the census-taking environment in 2000 will be
significantly more difficult than it was in 1990:  Mistrust of, and
cynicism about, the government and its programs has increased; people
are increasingly resistant to intrusions on their time; there is
increasing concern about privacy; the number of people working more
than one job has increased, along with the number of multiple-worker
families, so fewer people are home when an enumerator visits; and so
forth. 

Many major improvements planned for Census 2000 -- a better address
list, improved through partnerships with the U.S.  Postal Service and
local and tribal governments, easy to read and complete census forms,
fewer questions to answer, multiple opportunities to respond,
improved publicity, and improved procedures for dealing with those
who have no ï¿½usualï¿½ residence -- are needed to keep initial response
rates about even with those in 1990.  Studies from past censuses have
shown clearly that responses received by mail are of better quality
than those gathered by temporary field staff.  So high initial
response improves census quality and reduces census cost, freeing
resources to deal more effectively with the 33 percent of households
likely not to respond initially. 

Those households that do not respond initially are likely to have
attitudes that make finding and including them more difficult.  Thus,
in the absence of the ï¿½Quality Checkï¿½ operation planned for Census
2000, the Census Bureau believes it would need to implement several
additional procedures in an attempt to ensure a complete and accurate
census.  These activities would require the expenditure of additional
funds, even though the National Academy of Sciences, the Inspector
General for the Department of Commerce, and many others, view these
activities as only marginally effective.  The Census Bureau would
include the following activities because they are the only
alternatives to the Quality Check expected to deal with some aspects
of the total undercount and the differential participation rates
among various segments of the population. 

ï¿½Conduct Census Bureau followup visits at all vacant housing units --
not just a sample of them -- which increases requirements for
temporary field staff.  Added cost:  $200 million

ï¿½Conduct field followup visits for all incomplete questionnaires
(i.e., primarily data omissions), which increases requirements for
temporary field staff.  Added cost:  $150 million

ï¿½Expand partnership activities with state, local, and tribal
governments and with various community and business groups, which
increases the requirements for temporary field staff.  Added cost: 
$25 million to $50 million

ï¿½Further expand marketing and publicity activities through increased
media placements and Census Bureau outreach activities.  Added cost: 
$50 million to $100 million

ï¿½Deploy special activities and tactics (e.g., team enumeration and
blanket census tract coverage) not otherwise included in the plan for
Census 2000 to assure reaching those segments of the population
traditionally difficult to reach and typically among the most
undercounted.  Added cost:  $25 million to $50 million

ï¿½Further expand enumerator supervision to assure greater quality in
enumeration for nonresponse.  Added cost:  $25 million to $50 million

Even with these added activities and their associated costs, there is
no assurance that the Census Bureau would be able to hold the
undercount rate to the levels achieved in 1990:  We estimate the
undercount would go up to approximately 1.9 percent of the total
population.  And, it would cost more than alternative approaches from
which we would get better results! 

\l The Quality Check operation is estimated to cost $325 million.  An
obvious question is, ï¿½Why, if the Quality Check costs $325 million
and Alternative 2 does not include the Quality Check, does
Alternative 2 cost $300-400 million more than Alternative 3?ï¿½ The
answer is found in understanding that having a response from every
household (every address), plus responses from all people living in
group quarters (institutional facilities) and all other locations
where people without a usual address reside on Census Day (including
migrant workers and the people often referred to as ï¿½the homelessï¿½)
does not guarantee a complete enumeration of the population.  Even
when the Census Bureau accounted for every known address in the 1990
census, the census failed to include more than 4 million people. 
Only the Quality Check will find all the people missed by normal
decennial census procedures. 

Thus, in the absence of the ï¿½Quality Checkï¿½ operation planned for
Census 2000, the Census Bureau believes it would need to implement
several additional procedures in an attempt to ensure a complete and
accurate census.  These activities would require the expenditure of
an additional $500-600 million, the details of which are described in
footnote i.  The Census Bureau would include theses additional
activities because they are the only alternatives to the Quality
Check expected to deal with some aspects of the total undercount and
the differential participation rates among various segments of the
population. 

Adding $500-600 million in new activities, while subtracting $325
million for the Quality Check, adds a net of about $175-275 million
to the cost of Alternative 2.  In addition, performing the Evaluation
Study that will be needed to assess the completeness of Census 2000
in the absence of the Quality Check, adds an additional $125 million
to the cost of Alternative 2, for a net increase of $300-400 million
when compared with Alternative 3. 

\m This scenario provides a reference point for comparison with
earlier decennial census methods; it is not an alternative the Census
Bureau would ever propose to use again.  It assumes: 

ï¿½A 1990 census-taking environment in 2000;

ï¿½No partnerships with the U.S.  Postal Service or local and tribal
governments to improve the address list and the maps used to guide
temporary Census Bureau employees assigned to visit nonresponding
households;

ï¿½The continued use of 1990-style census forms designed to make
processing easy for computers, not respondents;

ï¿½Only one delivery of census forms to each address with no early
notices, no reminder post cards, and no replacement forms;

ï¿½No opportunity for responding via telephone;

ï¿½No opportunity to pick up blank census forms at convenient locations
if no form was delivered to the address of the person wishing to
respond;

ï¿½No use of U.S.  Postal Service knowledge about vacant housing units;

ï¿½No automated access to data tabulations for customer-specified
geographic areas and population groupings; and,

ï¿½No ï¿½Quality Checkï¿½ to significantly reduce or eliminate the
undercount in each state, each congressional district, and most local
and tribal governments, or to significantly reduce or eliminate the
differential undercounts among various segments of the population. 

\n The $4.8 billion figure was estimated in 1992 in response to a
question from the General Accounting Office.  Although the Census
Bureau has learned many things in the intervening five years, this
figure has been retained as a benchmark for purposes of comparison. 
It does not include improvements planned for Census 2000 to counter
the ongoing decline in the mail response rate, estimated to reach 55
percent without such improvements.

If the Census Bureau found it necessary to make nonresponse followup
visits at 45 percent of all households, instead of the 33 percent
expected when using the improved procedures planned for Census 2000,
the extra workload and cost would divert significant financial
resources away from improved publicity and local/tribal partnership
activities, as well as additional special procedures needed to deal
with the most reluctant residents at nonresponding addresses. 
Repeating 1990 census procedures also would require more followup
visits to apparently vacant housing units, and other procedures aimed
at trying to include the traditionally hard-to-count. 

\o The cost figure shown is higher than originally estimated because
of necessary refinements identified subsequent to excluding these
options from consideration for Census 2000. 

Source:  Bureau of the Census summary chart, footnotes, and
attachment (June 18, 1997). 

                                      (Attachment 1)

                                                    2000/1990 RATIOS
                               ----------------------------------------------------------
                       1990    Projecte
                      Census    d 2000                Not Hispanic               Hispanic
                     --------  --------  --------------------------------------  --------
                                                                                  (can be
State                                                           Amer.     API +       any
Codes                   TOTAL     Total     White     Black    Indian   "Other"     race)
--------  ---------  --------  --------  --------  --------  --------  --------  --------
          UNITED     248,709,   1.10423   1.04748   1.14896   1.14548   1.46646   1.40312
           STATES         873
63 01     Alabama    4,040,58   1.10147   1.09159   1.11352   1.06300   1.48703   1.47367
                            7
94 02     Alaska      550,043   1.18771   1.13427   1.22785   1.07502   2.32220   1.67618
86 04     Arizona    3,665,22   1.30893   1.23871   1.43201   1.22171   1.64231   1.55515
                            8
71 05     Arkansas   2,350,72   1.11939   1.11468   1.09301   1.22545   1.47510   1.78114
                            5
93 06     Californi  29,760,0   1.09278   0.91384   1.02155   0.92357   1.44806   1.38473
           a               21
84 08     Colorado   3,294,39   1.26525   1.22898   1.39307   1.36705   1.60175   1.40029
                            4
16 09     Connectic  3,287,11   0.99910   0.95210   1.12244   0.96790   1.43362   1.34820
           ut               6
51 10     Delaware    666,168   1.15220   1.10324   1.28455   1.07276   1.59955   1.60449
53 11     District    606,900   0.86230   0.91740   0.79814   0.67971   1.19415   1.24699
           of
           Columbia
59 12     Florida    12,937,9   1.17741   1.09811   1.26960   1.18241   1.54617   1.51884
                           26
58 13     Georgia    6,478,21   1.21558   1.15992   1.30216   1.21543   1.80126   1.74751
                            6
95 15     Hawaii     1,108,22   1.13461   1.04357   1.02558   1.15571   1.16397   1.32293
                            9
82 16     Idaho      1,006,74   1.33748   1.30453   1.90003   1.42914   1.55623   1.82060
                            9
33 17     Illinois   11,430,6   1.05426   1.00040   1.08302   0.99879   1.40220   1.40206
                           02
32 18     Indiana    5,544,15   1.09025   1.07505   1.15474   1.11493   1.46407   1.42174
                            9
42 19     Iowa       2,776,75   1.04432   1.02733   1.27244   1.19320   1.59977   1.62551
                            5
47 20     Kansas     2,477,57   1.07697   1.04678   1.18499   1.11482   1.46760   1.47784
                            4
61 21     Kentucky   3,685,29   1.08392   1.07860   1.09028   1.14045   1.47735   1.48194
                            6
72 22     Louisiana  4,219,97   1.04849   1.00561   1.11374   1.02292   1.37983   1.27807
                            3
11 23     Maine      1,227,92   1.02544   1.02216   0.91493   0.97796   1.36832   1.37853
                            8
52 24     Maryland   4,781,46   1.10314   1.01334   1.24195   1.10961   1.51274   1.72371
                            8
14 25     Massachus  6,016,42   1.03030   0.98139   1.20818   0.98018   1.45724   1.51768
           etts             5
34 26     Michigan   9,295,29   1.04127   1.01828   1.10506   1.04919   1.44585   1.28821
                            7
41 27     Minnesota  4,375,09   1.10393   1.06980   1.63299   1.25371   1.72112   1.75265
                            9
64 28     Mississip  2,573,21   1.09425   1.08019   1.10752   1.04004   1.54860   1.42941
           pi               6
43 29     Missouri   5,117,07   1.08272   1.06675   1.13972   1.17665   1.43599   1.45827
                            3
81 30     Montana     799,065   1.18846   1.17243   1.54728   1.25065   1.66946   1.68137
46 31     Nebraska   1,578,38   1.08051   1.05432   1.23405   1.21358   1.68420   1.62682
                            5
88 32     Nevada     1,201,83   1.55704   1.44317   1.67091   1.42260   2.07420   2.21791
                            3
12 33     New        1,109,25   1.10365   1.09617   1.06905   1.14838   1.47377   1.51390
           Hampshire        2
22 34     New        7,730,18   1.05790   0.97179   1.12152   1.14476   1.66426   1.41281
           Jersey           8
85 35     New        1,515,06   1.22793   1.19314   1.23095   1.22370   1.33586   1.27163
           Mexico           9
21 36     New York   17,990,4   1.00866   0.93419   1.03862   1.03730   1.40773   1.26675
                           55
56 37     North      6,628,63   1.17328   1.15627   1.19086   1.16099   1.74674   1.56188
           Carolina         7
44 38     North       638,800   1.03583   1.01661   1.36511   1.25615   1.62593   1.61886
           Dakota
31 39     Ohio       10,847,1   1.04348   1.02408   1.13818   1.07222   1.41716   1.31574
                           15
73 40     Oklahoma   3,145,58   1.07214   1.04141   1.19289   1.10532   1.39829   1.43386
                            5
92 41     Oregon     2,842,32   1.19521   1.15897   1.32502   1.25145   1.58609   1.71517
                            1
23 42     Pennsylva  11,881,6   1.02697   1.00368   1.10125   1.17127   1.48854   1.43937
           nia             43
15 44     Rhode      1,003,46   0.99416   0.94914   1.18525   1.16644   1.11675   1.65560
           Island           4
57 45     South      3,486,70   1.10650   1.09792   1.11148   1.03248   1.39562   1.41838
           Carolina         3
45 46     South       696,004   1.11648   1.09946   1.58438   1.20611   1.72261   1.68107
           Dakota
62 47     Tennessee  4,877,18   1.15992   1.14393   1.19369   1.29541   1.69500   1.76137
                            5
74 48     Texas      16,986,5   1.18443   1.09527   1.21758   1.14037   1.55113   1.35377
                           10
87 49     Utah       1,722,85   1.28102   1.24794   1.63259   1.46452   1.75503   1.61397
                            0
13 50     Vermont     562,758   1.09604   1.08778   1.48662   1.08601   1.68444   1.60148
54 51     Virginia   6,187,35   1.13086   1.07650   1.20923   1.08587   1.63047   1.67326
                            8
91 53     Washingto  4,866,69   1.20377   1.15636   1.22703   1.25074   1.64470   1.67648
           n                2
55 54     West       1,793,47   1.02649   1.02270   1.02458   1.01100   1.40708   1.46413
           Virginia         7
35 55     Wisconsin  4,891,76   1.08883   1.05972   1.31732   1.19069   1.78329   1.44430
                            9
83 56     Wyoming     453,588   1.15678   1.13747   1.28955   1.33115   1.65389   1.33373
-----------------------------------------------------------------------------------------
Source:  Bureau of the Census summary chart, footnotes, and
attachment (June 18, 1997). 




(See figure in printed edition.)Appendix III
COMMENTS FROM THE BUREAU OF THE
CENSUS
========================================================== Appendix II


MAJOR CONTRIBUTORS TO THIS REPORT
========================================================== Appendix IV

GENERAL GOVERNMENT DIVISION

James H.  Burow, Assistant Director
Victoria E.  Miller, Evaluator-in-Charge
Timothy A.  Bober, Senior Evaluator
Jacqueline E.  Matthews, Senior Evaluator
Kiki Theodoropoulos, Senior Evaluator (Communications Analyst)
Thomas M.  Beall, Technical Advisor
Thomas B.  Jabine, Statistical Consultant

NATIONAL SECURITY AND
INTERNATIONAL AFFAIRS DIVISION

Arthur J.  Kendall, Senior Mathematical Statistician

OFFICE OF GENERAL COUNSEL,
WASHINGTON, D.C. 

Alan N.  Belkin, Assistant General Counsel
James M.  Rebbe, Attorney-Advisor




RELATED GAO PRODUCTS
============================================================ Chapter 0

Addressing the Deficit:  Budgetary Implications of Selected GAO Work
for Fiscal Year 1998 (GAO/OCG-97-2, Mar.  14, 1997). 

High-Risk Series (GAO/HR-97-1 and 97-2, Feb.  1997). 

Addressing the Deficit:  Updating the Budgetary Implications of
Selected GAO Work (GAO/OCG-96-5, June 28, 1996). 

Decennial Census:  Fundamental Design Decisions Merit Congressional
Attention (GAO/T-GGD-96-37, Oct.  25, 1995). 

Addressing the Deficit:  Budgetary Implications of Selected GAO Work
for Fiscal Year 1996 (GAO/OCG-95-2, Mar.  15, 1995). 

Decennial Census:  1995 Test Census Presents Opportunities to
Evaluate New Census- Taking Methods (GAO/T-GGD-94-136, Sept.  27,
1994). 

Decennial Census:  Promising Proposals, Some Progress, but Challenges
Remain (GAO/T-GGD-94-80, Jan.  26, 1994). 

Decennial Census:  Test Design Proposals Are Promising, but
Fundamental Reform Is Still at Risk (GAO/T-GGD-94-12, Oct.  7, 1993). 

Decennial Census:  Fundamental Reform Jeopardized by Lack of Progress
(GAO/T-GGD-93-6, Mar.  2, 1993). 

Transition Series:  Commerce Issues (GAO/OCG-93-12TR, Dec.  1992). 

Decennial Census:  1990 Results Show Need for Fundamental Reform
(GAO/GGD-92-94, June 9, 1992). 

1990 Census:  Reported Net Undercount Obscured Magnitude of Error
(GAO/GGD-91-113, Aug.  22, 1991). 

1990 Census Adjustment:  Estimating Census Accuracy--A Complex Task
(GAO/GGD-91-42, Mar.  11, 1991). 

Progress of the 1990 Decennial Census:  Some Causes for Concern
(GAO/T-GGD-90-44, May 21, 1990). 

Critical Issues for Census Adjustment:  Completing Post Enumeration
Survey on Time While Protecting Data Quality (GAO/T-GGD-90-15, Jan. 
30, 1990). 


*** End of document. ***