APPENDIX
Sampling in the 2000 Census Interim Report I

Andrew A. White and Keith F. Rust, Editors

Panel to Evaluate Alternative Census Methodologies

Committee on National Statistics

Commission on Behavioral and Social Sciences and Education

National Research Council



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Preparing for the 2000 Census: Interim Report II APPENDIX Sampling in the 2000 Census Interim Report I Andrew A. White and Keith F. Rust, Editors Panel to Evaluate Alternative Census Methodologies Committee on National Statistics Commission on Behavioral and Social Sciences and Education National Research Council

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Preparing for the 2000 Census: Interim Report II NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. This report has been reviewed by a group other than the authors according to procedures approved by a Report Review Committee consisting of members of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Bruce M. Alberts is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Harold Liebowitz is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Kenneth I. Shine is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Bru ce M. Alberts and Dr. Harold Liebowitz are chairman and vice chairman, respectively, of the National Research Council. This project is supported by funds provided by the Bureau of the Census, U.S. Department of Commerce, under contract number 50-YABC-5-66005 Additional copies available from: Committee on National Statistics National Research Council 2101 Constitution Avenue, N.W. Washington, D.C. 20418 Printed in the United States of America Copyright 1996 by the National Academy of Sciences. All rights reserved.

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Preparing for the 2000 Census: Interim Report II CONTENTS     INTRODUCTION   89     BENEFITS OF SAMPLING   90     SAMPLING FOR NONRESPONSE FOLLOW-UP   92     INTEGRATED COVERAGE MEASUREMENT   96     FINAL COMMENTS   97     REFERENCES   98

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Preparing for the 2000 Census: Interim Report II INTRODUCTION This first interim report of the Panel on Alternative Census Methodologies focuses on the use of statistical procedures, especially sampling, in the conduct of the 2000 census. The panel has examined the research memoranda (Bureau of the Census, 1995-1996) resulting from the 1995 census test in Paterson, New Jersey, Oakland, California, and northwest Louisiana. We have also heard presentations provided by staff of the Bureau of the Census on the test and their work. Additional analysis of the 1995 census test is anticipated, and further information will be available from the 1996 census test. However, since decisions concerning many important features of the 2000 census are now being made by the Bureau of the Census, the panel believes that it is timely to offer its assessment on certain aspects of the design for the 2000 census. The Census Bureau has proposed a new design for the year 2000 census that includes sampling to follow up households that do not mail back their questionnaires or provide a telephone response. Sampling will also be used as part of an integrated coverage measurement1 procedure to obtain as complete a count as possible and to reduce differential undercoverage among areas and population groups. The 1990 census, in contrast, attempted to count every household by personal follow-up of those households that did not return a mail questionnaire. These procedures were both expensive and did not yield the desired goal: estimated by demographic analysis, 1.8 percent of the population was not counted in 1990 (up from 1.2 percent in 1980), including an estimated 5.7 percent of blacks. Hispanics, Asian and Pacific Islanders, American Indians and Alaska Natives, renters, and residents of poor inner-city areas were also undercounted by larger percentages than the nation as a whole (Edmonston and Schultze, 1995). Demographic analysis has estimated that the undercount rate was higher in 1990 than in 1980, after steadily decreasing since 1940. In 2000, the Census Bureau is likely to face an environment of constrained funding, decreasing survey response rates (Edmonston and Schultze, 1995), increasing cynicism toward government, and decreasing availability of a qualified temporary work force (Stuart, 1995). Consequently, it is likely that repeating 1990 methods with the same relative level of resources to conduct the 2000 census will yield results that are of worse quality than obtained in 1990 and that have bias and undercoverage problems of unknown size and direction at levels of geography not addressed by subsequent post-enumeration surveys. To reduce costs, increase response, increase accuracy across the various levels of geography, and reduce differential undercoverage of population groups and among areas, the Census Bureau is redesigning the census process. The Census Bureau has identified innovative ways to improve the response rate of households and to use sampling and statistical estimation 1   See the report of the Panel to Evaluate Alternative Census Methods (Steffey and Bradburn, 1994) for a discussion of coverage measurement.

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Preparing for the 2000 Census: Interim Report II techniques as integral parts of the census enumeration methodology that are needed to deal cost-effectively with household nonresponse. These techniques are critical to the success of the year 2000 census. The panel is very encouraged by the considerable progress that the Census Bureau has made in work on improving response (by mail or telephone) to the questionnaire, including: redesigning the questionnaire, facilitating response to the mail questionnaire with reminders and a replacement questionnaire, providing multiple response options including use of the telephone and Be Counted forms,2 use of non-English questionnaires, use of partnerships with local officials, advertising and other outreach efforts, use of service-based and special targeted enumeration methods, and developing in cooperation with local governments (and the U.S. Postal Service) a full and accurate master-address list geographically referenced to the street locations in the TIGER (Topologically Integrated Geographic Encoding and Referencing) database. Many of these initiatives are new to decennial census procedures, and the significant improvements documented in the 1995 census test research memoranda on these ideas demonstrate serious efforts at revising the census process towards the goals of reducing costs, increasing response and accuracy, and reducing differential undercoverage for population subgroups. The panel intends to comment further on these initiatives in its subsequent reports; however, this report addresses only the use of sampling and statistical procedures in the 2000 census because of the Census Bureau's need to make decisions immediately on these topics. BENEFITS OF SAMPLING Even with the potential for great improvement in the 2000 census through use of the operational initiatives mentioned above, the use of sampling and other statistical procedures will be fundamental to achieving the goals of reduced costs, increased accuracy, and reduced differential undercoverage. The panel endorses the general recommendations of both the Panel to Evaluate Alternate Census Methods (Steffey and Bradburn, 1994) and the Panel on Census Requirements (Edmonston and Schultze, 1995). We support the use of sampling procedures in the follow-up of households that do not respond by mail (or telephone call) to the census (sampling for nonresponse follow-up). We also endorse the recommendations of those panels to use sampling procedures to collect relevant data that will be used in conjunction with the appropriate statistical procedures to derive a final enumeration that has acceptably low levels of differential undercoverage and other enumeration errors (sampling for integrated coverage measurement). The Census Bureau's use of sampling for these purposes is consistent with past approaches. We note that the Census Bureau has expertise second to none in the many aspects of sampling and in fact has a long history of applying sampling to certain parts of census operations (Goldfield, 1992). The research memoranda that the panel has seen from the 1995 census test give valuable insight into which components of the operations for nonresponse follow-up and integrated coverage 2   Be counted forms are unaddressed census questionnaires available in public places.

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Preparing for the 2000 Census: Interim Report II measurement succeeded and which components require further research for the 2000 census. Although some design decisions remain to be made and tested, the panel argues below that nothing in the census test, nor any other development, suggests that a decennial census that reduces costs, reduces nonresponse bias, increases accuracy, and reduces differential undercoverage can be conducted without the use of some form of sampling for mail nonresponse follow-up and some form of sampling for integrated coverage measurement. The traditional census method (used in 1990) begins with the mailing of census forms to a comprehensive list of residential addresses. For households that do not respond to the mail questionnaire, census enumerators undertake an intensive follow-up effort to contact the households and elicit responses. This process is continued for an extended period of time in an attempt to physically enumerate every household and all the people in every household. Despite the gains in address list development, form design, prenotice and reminder mailings, and various outreach efforts, exclusive reliance on physical enumeration of all households cannot be successful in 2000. Based on the results of the 1990 census, it is highly unlikely that the Census Bureau can carry out this type of decennial census with acceptable accuracy within the current expected levels of funding. An effort to conduct a census in 2000 using 1990 methods--that is, attempting to the fullest extent to physically enumerate every household, with the funding levels that now seem probable--will likely result in a census of substantially lower quality than previous censuses. That lower quality will be readily apparent to all knowledgeable users of census data. The panel's view that sampling and statistical estimation are essential ingredients to the 2000 census does not derive only from a concern that there will not be sufficient resources to pay for using 1990 methods. Even if the resources were available to conduct such a census, we believe it is likely that the use of statistical procedures can allow more effective use of those resources. Our view that statistical procedures can improve quality at any census funding level is based on several limitations of the 1990 census and earlier censuses that are not always recognized in discussions of the relative merits of statistical procedures. We have considered four issues. First, there is an issue of timeliness. Any approach that attempts physically to enumerate every household through several field visits invariably takes considerable time to complete. The amount of time varies considerably by area, depending upon the mail return rate and the difficulty in contacting households. More important, it is inevitable that the quality of the information obtained from those households contacted late is of lesser quality than information from other households. Respondents simply do not remember or know who exactly was present on census day, or the characteristics of those people. A second, related issue is that there is a biased and uncontrolled sample of cases left over at the end of every field period about which little is known. Census forms for these households are inevitably completed using information from neighbors, landlords, and others. These "last-resort" cases constitute a significant proportion of census returns in some areas: in 1990 they accounted for nearly 4 percent of all households in the country. Although the information on these households is useful, it must be recognized that these data are collected by temporary employees who are generally inexperienced and under considerable pressure to complete their workloads in a timely fashion and that these data are often of much lower quality than those collected on the returned questionnaires and from field follow-up of household occupants. Therefore, last-resort data are not necessarily more reliable than

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Preparing for the 2000 Census: Interim Report II estimates based on statistical methods, although they are likely to be much more expensive. (Further analysis of these last-resort cases would be extremely valuable for understanding when they are and are not reliable and how to best make use of this information.) This discussion leads to a third issue, which is the availability of a work force that is capable of competently carrying out the census enumeration. Census takers are temporary employees, paid at a low hourly rate, who must be recruited locally in all areas of the country--most heavily in those areas with the lowest mail return rates. Evidence from the 1990 decennial census (Stuart, 1995) and from the 1995 census test strongly suggests that it will not be possible to locate enough temporary competent employees to complete a 100 percent mail nonresponse follow-up in the 2000 census. Even if it were possible, the cost would greatly exceed current expected levels of funding. Furthermore, it is likely that the areas with the lowest mail return rates and the highest concentration of groups that historically have been undercounted in the census are also those in which it will be most difficult to find sufficient numbers of enumerators. Fourth, there is ample evidence from recent censuses that the methods used in the 1990 census resulted in a substantial amount of both undercoverage and erroneous enumeration and that these errors are very differentially spread across demographic and geographic subgroups. From the 1990 experience, attempts to contact every household that does not return a form by mail do not appear capable of reducing these problems, and especially the differential undercount, to any appreciable extent. Although the initiatives to improve the master address list, develop outreach, make use of respondent-friendly instruments, use reminder cards, and other process improvements will help to reduce undercoverage and erroneous enumeration, we see no evidence from the 1995 census test to suggest that these enhancements alone will come acceptably close to eliminating the undercoverage and erroneous enumeration problems. The combination of the problems mentioned above indicates that it will also be necessary to include procedures for sampling for nonresponse follow-up (to address the first three issues) and for integrated coverage measurement (to address the fourth issue). In the next two sections we discuss these procedures in more detail. SAMPLING FOR NONRESPONSE FOLLOW-UP In addition to addressing the limited work force problem, sampling for nonresponse follow-up provides an effective means of addressing the related issues of timeliness, the use of last-resort returns, and the quality of field enumeration. By requiring that only a sample of those households that do not return a form by mail or telephone be followed up, more effort can be concentrated on the process of completing household enumeration in a given area, which can be carried out more quickly and more intensively (so that there remain fewer nonresponding cases that require last-resort procedures), and which can make use of better trained, more experienced personnel. Thus, the introduction of sampling will reduce other sources of error inherent in operations. These benefits of sampling are well recognized in survey research and are generally accepted when survey instruments are involved. The panel believes that these benefits are also likely to be substantial in the decennial census.

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Preparing for the 2000 Census: Interim Report II It is not realistic to expect that costs, staffing, and time expended will all decrease in direct proportion to the sampling rate. Thus, a decision to sample 25 percent of households (not returning a form by mail) in an area does not mean that the enumeration can be done in one-quarter of the time, using one-quarter of the field staff, with the elimination of last-resort enumerations. However, the enumeration can very likely be done in less time than would a full enumeration, using fewer staff, and with a smaller fraction of last-resort enumerations. It is for this reason that the panel believes that sampling for nonresponse follow-up needs to be an integral part of the plans for the 2000 census. In discussing the comparative accuracy of census counts and the quality of census data with alternative methodologies, it is very important to consider the uses of census data. In particular, the effects of sampling on the accuracy of counts and other data will differ by the level of geography. In concluding that procedures for sampling for nonresponse follow-up will give better results than use of 100 percent follow-up, the panel is considering the use of data at broad and intermediate levels of geography, such as those identified in constitutional and legislative requirements for the use of census data. In sampling, a measurable sampling variance will be substituted for the bias resulting from an uncontrolled sample. Thus, for enumerating the populations of states, congressional districts, state legislative districts, and many governmental units, we believe that it is likely that reductions in errors and omissions in enumeration will outweigh the introduction of sampling error. However, for sufficiently small levels of geography, this assertion may not hold because sampling error (relative to the size of the population) increases as the population of a geographic area decreases. Other errors are more likely to have effects of similar relative magnitude at all geographic levels (although they will vary across geographic units, at any given level). Therefore, at the block level, for example, it seems unlikely that the average level of (relative) error will be less when sampling is used (although this conclusion would depend upon the extent of sampling). There is a tradeoff between the demands for accuracy for very small geographic areas and those of larger areas. In the panel's view, the needs for data for larger domains should take precedence. For example, while block unit data are important, they are almost always aggregated to form larger geographic areas. When such aggregation occurs, the relative effects of sampling error decrease, and the benefits of sampling for nonresponse follow-up will tend to outweigh the effects of sampling error. Sampling for nonresponse does not introduce bias when particular groups are sampled at higher or lower rates because appropriate methods will be used to create the final counts that account for the designed variations in sampling rate. In sum, it appears that the error introduced by sampling at the block and tract levels would not vitiate the value of census data for research and policy making. Another significant concern about census operations involves equity. It is important that the procedures used ensure results of uniform (and acceptable) quality for geographic areas or groups of similar size. The use of sampling for nonresponse follow-up has great potential to further this aim. In contrast, there is substantial evidence that the use of 100 percent follow-up of mail nonresponse in the 1990 census did not result in uniform and high quality to a satisfactory extent. There was considerable variation in the use of last-resort enumerations for different geographic regions, and it has been clearly demonstrated that census undercoverage varied greatly across geographic and demographic groups. Much

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Preparing for the 2000 Census: Interim Report II money and effort were concentrated at the end of the census operations but data quality decreased at the same time. The use of sampling for nonresponse follow-up has an equitable effect in that, on average, no group's estimated population is made systematically larger or smaller by sampling, regardless of whether certain groups have lower response rates and regardless of the rate of sampling among nonrespondents. A secondary issue is that estimates for some groups, particularly in small areas, may be less precise (although not systematically biased either upwards or downwards) because high nonresponse makes these estimates more dependent on sampling. It is possible to attain more nearly uniform accuracy for areas of comparable size by appropriate choices of sampling rates. Similarly, it is also possible to provide greater accuracy for small political units than for comparably sized areas that are not political divisions by appropriate sample allocation. Consideration of these tradeoffs within the budget allocated to sampling will be part of the sample design process. The use of sampling for nonresponse follow-up gives reasonable promise that accuracy can be improved and differences in the quality of enumeration can be diminished by concentrating the efforts of better enumerators on the sampled cases. While there should be gains in accuracy for all areas, those places where the methods used in 1990 were the least successful, and produced the most bias, stand to benefit most, in terms of improved accuracy of enumeration, through the adoption of sampling for nonresponse follow-up. Although the panel endorses the use of sampling for nonresponse follow-up as part of the operations for the 2000 census, the decisions concerning the design of the sampling plan should not be made without due consideration of a broad range of issues. Six issues that need to be considered are: (1) the levels of sampling and other error across geographic units at different levels of aggregation; (2) the costs of enumerating different types of households that do not respond by mail; (3) the estimation methodology; (4) how the estimation will be implemented in practice; (5) the timing of the data collection; and (6) the public perception of the use of sampling. The Bureau of the Census should adopt a systematic approach to developing a good sample design and associated estimation procedure. This cannot necessarily be achieved by postulating a small number of designs and determining which appears to optimize various criteria. Some further exploration of criteria is needed. We offer several examples of the need to proceed in this manner. First, consider two ways to truncate full-scale direct enumeration prior to initiating sampling for nonresponse follow-up: (1) after a given date (this procedure is called the direct application of sampling), and (2) after a given fraction of the population has been counted in an area. It has been suggested (Killion, 1995) that the former would be superior to the latter. Consideration only of sample size and sampling error, using an assumption that every household costs the same to enumerate, shows that this conclusion obtains. However, some households are more expensive to enumerate than others. Assuming a fixed number of completed household enumerations and comparing direct versus truncated sampling then yields the result that direct application of sampling will likely sample these higher cost cases at a substantially greater rate than a plan that introduces sampling after some threshold response rate is achieved. By continuing to enumerate physically to a threshold without sampling, a larger percentage of the less costly cases may be completed. Second, conversely, it has been suggested (Killion, 1995) that a plan that enumerates

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Preparing for the 2000 Census: Interim Report II 90 percent and then samples 1 in 10 remaining households would be more acceptable than a plan that enumerates 70 percent and then samples 7 in 10 households (for example). Both of these procedures result in data collection from 91 percent of households. The view is that the former is seen as placing much less reliance on sampling than the latter. But the public perception of the reliance on sampling might be represented as well by the number of households that each sampled household is expected to represent as by the size of the population represented by sampling. In this case, it is not clear that having each sampled household represent nine others3 is preferable to having each sampled household represent itself and possibly one other. Moreover, we believe that the issue of truncation cut-off points should be resolved scientifically, using statistical criteria and examining the expected sampling variance at various levels of geography. Such a resolution could consider operational criteria such as the percentage of responses after a certain period of time. A variable cut-off strategy depending on local response rates could also be considered. Third, up to the present, the Bureau of the Census has proposed 100 percent followup until either 70 percent or 90 percent of a region has been physically enumerated. This choice begs the question as to whether some other percentage might produce superior results. Indeed, the best performance may come from a design with a variety of different truncation percentages to optimize enumeration in different areas. Finally, and perhaps most important, the advantages of a given sampling scheme will depend dramatically on the level of geography at which it is implemented. For example, a scheme that requires 90 percent completion at the block level before going to sampling will have greatly different characteristics than one that requires 90 percent completion at the county level. The former will be much more expensive than the latter, but the latter would lead to very great inequities in the level of precision available at various lower levels of geographic aggregation, e.g., at the tract level within each county. A county will often include areas that differ greatly with respect to census enumeration, e.g., areas with high and low mail back response, and areas with easy and difficult field follow-up. If the completeness criterion is set at the county level, then higher rates of completion will be obtained where it is easiest and other areas may still have much lower completion rates. It is important to win general acceptance of the concept of sampling for nonresponse follow-up. Although it may be necessary to propose some examples for public debate, the Census Bureau should not constrain itself to choose a specific and possibly oversimplified design at this time. Thus, the panel urges the Bureau to continue to apply a flexible approach to developing a sampling scheme for nonresponse follow-up on the basis of the results of the 1990 census and the 1995 test census in order to achieve a sensible balance among all of the important considerations. This might include different truncation points and different sampling rates in different places. This plan must be based on reasonable cost assumptions and must integrate the estimation and imputation procedures into its design. We recognize, however, that 2000 is fast approaching, and the Census Bureau should identify the most promising design(s) as soon as possible. 3   With the use of imputation, this is a literal statement.

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Preparing for the 2000 Census: Interim Report II INTEGRATED COVERAGE MEASUREMENT As indicated above, even with the successful implementation of the various improvements in census methodology explored in the 1995 census test (other than sampling and statistical procedures), there will remain some people who are missed and some smaller degree of erroneous enumeration. These coverage errors will undoubtedly occur differentially across geographic areas and among different population subgroups, as they have in past censuses. Because this systematic error component will dominate other forms of error at broad levels of aggregation, it is essential to use integrated coverage measurement in the process of computing the final census count. Integrated coverage measurement involves two steps: first, sampling is used to identify the nature of the undercoverage problem; second, statistical procedures are used to incorporate the results of the sampling. Such integrated coverage measurement, as part of the census, is critical to reducing the differential undercount among population groups. Integrated coverage measurement in 2000 will differ from the coverage measurement component of previous censuses in several important ways. Two key instances are that it will have a larger sample size so that accurate estimates can be made at lower levels of aggregation, and it will be completed earlier than the postenumeration survey conducted in 1990. In addition, integrated coverage measurement will account for a larger fraction of the census count because it will replace several coverage improvement activities used in recent censuses, such as the recanvass operations and the parolee/probationer check. It will also partially replace vacancy/delete operations. In addition, it will be more closely connected operationally and temporally with the major census field activity and therefore will be a more integral and necessary part of completing an accurate census. The panel also sees an important interrelationship between the operations of the nonresponse follow-up plan and integrated coverage measurement. The quality of the integrated coverage measurement operation will almost certainly be affected by the length of delay between census day and the conduct of the integrated coverage measurement interview. With a longer time interval, it will be more difficult to get accurate information from a respondent about the household on census day. Also, a greater proportion of households will have moved, contributing substantially to the difficulty of obtaining accurate information. The use of sampling for nonresponse follow-up offers the potential to minimize any time interval between the date of the census and the conduct of the integrated coverage measurement interview. Minimizing the delay improves the quality of the census counts. Moreover, an integrated coverage measurement program, based necessarily on a relatively small sample, argues in favor of the use of sampling for nonresponse follow-up. Since a component of the final count is to be based on data from the integrated coverage measurement sample, a consideration of the total error of the census as a whole argues that it is not logical to expend tremendous resources to enumerate every last household physically prior to integrated coverage measurement. A portion of those resources would be better spent increasing the size of the integrated coverage measurement sample used in combination with nonresponse follow-up sampling. The Census Bureau's plans for selecting an integrated coverage measurement procedure involve comparing the performance of a dual systems estimation approach with the

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Preparing for the 2000 Census: Interim Report II performance of a new methodology called Census Plus. The panel expects to learn more about the performance of these alternative approaches to integrated coverage measurement in the 1995 census test in its continuing work and to comment on them in a subsequent report. At this juncture, the panel endorses the use of integrated coverage measurement without commenting on the two specific approaches being considered. The panel emphasizes that the success of any approach depends heavily on the structure of the integrated coverage measurement interview and the rules used to establish the list of persons present on census day. The Census Bureau has identified deficiencies in this regard in the 1995 census test, which were to be expected with the first trial of a novel approach. The panel is very much encouraged by the rapid developments that have taken place in this area in the months since the 1995 census test, and the panel is optimistic that a sound set of procedures can be in place for the 2000 census. FINAL COMMENTS A combination of sampling for nonresponse follow-up and for integrated coverage measurement is key to conducting a decennial census at an acceptable cost, with increased accuracy and overall quality, and reduced differential undercoverage. Sampling and statistical procedures build on the strengths of traditional census operations to collect the information quickly, reduce the dependence on last-resort information, and aid in the development of a competent enumeration staff. Building on considerable evidence from past Census Bureau tests that it is feasible to conduct follow-up sampling to reduce cost and nonresponse to field follow-up, the 1995 census test has provided sound evidence that mail nonrespondents can be followed up effectively on a sample basis and that sampling for nonresponse follow-up can be integrated successfully with coverage improvement sampling. The Census Bureau has made considerable progress in a wide range of techniques for conducting the census, including sampling, to improve the 2000 decennial census. The panel intends to comment further on these initiatives in its subsequent reports.

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Preparing for the 2000 Census: Interim Report II REFERENCES Bureau of the Census 1995-Census Test Results Memorandum Series, Nos. 1-46. Bureau of the Census, 1996. U.S. Department of Commerce, Washington, D.C. Edmonston, B., and C. Schultze, eds. 1995   Modernizing the U.S. Census. Panel on Census Requirement in the Year 2000 and Beyond, Committee on National Statistics, National Research Council. Washington, D.C.: National Academy Press. Goldfield, Edwin D. 1992   Innovations in the Decennial Census of Population and Housing: 1940-1990. Paper prepared for the Committee on National Statistics, Commission on Behavioral and Social Sciences and Education, National Research Council, Washington, D.C. Killion, R.A. 1995   Agenda for October 31, 1995 SESC Meeting., Unpublished memorandum, Bureau of the Census, U.S. Department of Commerce, Washington, D.C. Steffey, D.L., and N.M. Bradburn, eds. 1994 Counting People in the Information Age. Panel to Evaluate Alternative Census Methods, Committee on National Statistics, National Research Council. Washington, D.C.: National Academy Press. Stuart, J. 1995   2000 Decennial Census Labor Force Issues: Escalating Enumeration Costs. Unpublished paper, Bureau of the Census, U.S. Department of Commerce, Washington, D.C.