3
Addresses Linked to Geography: Cornerstone of the 2000 Census

An accurate geographic representation of the territory to be enumerated, in both cartographical and digital form, and a complete list of addresses referenced to their correct geographic location are crucial to the success of the proposed methodology for the 2000 census. A census that counts people at their usual place of residence requires a geographic framework that delineates the territory where dwellings are located, includes the addresses of all dwelling units, and ensures that these dwelling units are referenced to their correct geographic location. This is essential for accurate census counts and for statistical data for small geographic areas. Both the association of census responses with their correct locations and the inclusion of locations within the correct tabulation areas depend on the accuracy of the geographic framework and the address list. In addition, several of the important methodological innovations being introduced in the 2000 census assume and depend on an accurate geographic framework and an accurate list for their success.

The degree of precision required in the geographic framework for the census has evolved over time as the need for finer and finer small-area data has increased. For the 2000 census, dwellings need to be pinpointed very precisely in order to allow the aggregation of census counts and statistical data for many geographic areas, including those user-defined areas that do not respect the boundaries of the standard geographic areas. With the introduction of the Topologically Integrated Geographic Encoding and Referencing (TIGER) system in the 1990 census, the framework for identifying the precise geographic location of each dwelling was established. While TIGER provides the geographic framework within which every dwelling (as well as many other physical features) can be located, it does not provide a list of dwellings. Such a list of dwellings, the Master Address File (MAF), linked to the correct geographic location in TIGER, is crucial to the successful implementation of the 2000 census methodology.

Prior to 1970, when censuses were conducted completely by direct enumeration, the interviewers created the list of dwellings as they covered their territory. With the introduction of a mail census, a list of dwellings was needed prior to the actual census as the basis for mailing questionnaires. Up to and including the 1990 census, these initial lists were created anew for each census, using commercial and other sources. Dwellings might be added to these initial lists during the census enumeration and follow-up activities.

For the 2000 census, the plan is to create the initial MAF, not from scratch, but from the final 1990 census dwelling list, updated through a variety of sources, including the U.S. Postal Service (USPS), local governments, and, possibly, private companies. The goal is to develop an updating system that will eventually ensure the availability of a current MAF at all times. The case for such a continuously updated MAF does not rest on census considerations alone, but also on the potential uses of such a list for other



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Preparing for the 2000 Census: Interim Report II 3 Addresses Linked to Geography: Cornerstone of the 2000 Census An accurate geographic representation of the territory to be enumerated, in both cartographical and digital form, and a complete list of addresses referenced to their correct geographic location are crucial to the success of the proposed methodology for the 2000 census. A census that counts people at their usual place of residence requires a geographic framework that delineates the territory where dwellings are located, includes the addresses of all dwelling units, and ensures that these dwelling units are referenced to their correct geographic location. This is essential for accurate census counts and for statistical data for small geographic areas. Both the association of census responses with their correct locations and the inclusion of locations within the correct tabulation areas depend on the accuracy of the geographic framework and the address list. In addition, several of the important methodological innovations being introduced in the 2000 census assume and depend on an accurate geographic framework and an accurate list for their success. The degree of precision required in the geographic framework for the census has evolved over time as the need for finer and finer small-area data has increased. For the 2000 census, dwellings need to be pinpointed very precisely in order to allow the aggregation of census counts and statistical data for many geographic areas, including those user-defined areas that do not respect the boundaries of the standard geographic areas. With the introduction of the Topologically Integrated Geographic Encoding and Referencing (TIGER) system in the 1990 census, the framework for identifying the precise geographic location of each dwelling was established. While TIGER provides the geographic framework within which every dwelling (as well as many other physical features) can be located, it does not provide a list of dwellings. Such a list of dwellings, the Master Address File (MAF), linked to the correct geographic location in TIGER, is crucial to the successful implementation of the 2000 census methodology. Prior to 1970, when censuses were conducted completely by direct enumeration, the interviewers created the list of dwellings as they covered their territory. With the introduction of a mail census, a list of dwellings was needed prior to the actual census as the basis for mailing questionnaires. Up to and including the 1990 census, these initial lists were created anew for each census, using commercial and other sources. Dwellings might be added to these initial lists during the census enumeration and follow-up activities. For the 2000 census, the plan is to create the initial MAF, not from scratch, but from the final 1990 census dwelling list, updated through a variety of sources, including the U.S. Postal Service (USPS), local governments, and, possibly, private companies. The goal is to develop an updating system that will eventually ensure the availability of a current MAF at all times. The case for such a continuously updated MAF does not rest on census considerations alone, but also on the potential uses of such a list for other

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Preparing for the 2000 Census: Interim Report II statistical purposes (see Steffey and Bradburn, 1994). Thus, the plan and schedule for MAF have been designed to satisfy not only the needs of the 2000 census, but also the continuous measurement needs of the American Community Survey.1 From the viewpoint of the census alone, there are several benefits of a continuously updated MAF: it provides a smoother or more level work flow, avoiding huge precensus peaks that may be difficult to staff; it provides the opportunity for continuing partnerships with census participants and users, especially local governments; and it facilitates the use of quality control programs that should lead to a higher quality list. With the innovations in methodology proposed for the 2000 census, the fundamental importance of an accurate MAF and TIGER database to the success of the census is significantly increased. As subsequent chapters illustrate, the offering of alternative means of response, the use of sample nonresponse follow-up, and the plans for integrated coverage measurement all depend on having a reliable dwelling list, referenced to correct geographic locations. For example, the matching of information coming from "Be Counted" forms to the census database requires complete and unambiguous address and geographic area identification. The success of both nonresponse follow-up and integrated coverage measurement is contingent on an accurate MAF with clearly identified dwelling units linked to the correct geographic locations. Although the quality of the initial lists was always important for the initial mail-out of census form, it takes on added importance with the introduction of methodology for the 2000 census. The quality of the initial MAF and its linkages to TIGER may well be the single most important factor determining the success of the 2000 census. Parallel updating of the representation of geographic features in TIGER and of dwellings in MAF is not only necessary but efficient. Information sources that generate new addresses will often simultaneously generate geographic features, especially roads and streets, that must be added to TIGER, and vice versa. But equally as important as the current individual updating of TIGER and MAF is the currency of the linkage between them. In updating these sources in parallel, it is important to carefully manage their linkages and vintages. Since some census-taking tools (e.g., maps) are derived from TIGER, while others (e.g., address listings) are derived from MAF, the two databases must be properly linked. Addresses or features reflected in one but not the other, or maps and address lists coming from asynchronous versions of the two databases, can lead to confusion and loss of confidence by local government officials who are helping to improve these databases and by census field staff who are relying on them to take the census. 1   The American Community Survey (ACS) is designed to update regularly the information about communities that the U.S. census has traditionally produced once a decade. "Communities" include geographic areas of all sizes and demographic subgroups (Alexander, 1996).

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Preparing for the 2000 Census: Interim Report II NEED FOR AN ACCURATE MAF The completeness of the initial MAF and its accurate referencing to TIGER will play a crucial role in the success of the 2000 census. Although dwellings can be added to the MAF during the enumeration process, the more dwellings that can be accurately included in the initial MAF, the smoother and more efficient will be the enumeration process. Therefore, investment in an accurate MAF, with integrated linkage to TIGER, should have a very high priority in Census Bureau work. The challenge faced by the Census Bureau is to develop the best possible initial MAF given available resources. This challenge involves assuring not only a high average quality level, but also a uniformly high quality level. Since much of the output of the census is data for local areas, the census cannot afford to have areas for which the coverage of dwellings is deficient, even if on average it is very good. Yet it is recognized that whatever methods are used for creating the initial MAF, there are bound to be some areas for which it is not possible to create an adequate initial version. In such areas, census methodology will have to be able to compensate for these deficiencies through special enumeration efforts or other procedures. Five general aspects of the challenge should determine the approach to be used. First, because the territory to be covered is vast and local knowledge is an important ingredient in creating and maintaining an accurate geographic framework with a linked address list, the Census Bureau cannot expect to do this task alone. Partnership is necessary. There are many potential partners who have an interest in a strong geographic framework and a complete address list for the census, including local governments as users of census data, data marketers, and other organizations, such as the USPS, which also requires accurate geographic representation of the country. Second, the difficulty of keeping TIGER and MAF up to date varies greatly across the country. Some relatively stable areas present few problems, while high-growth areas or areas of urban renewal may be very challenging. Urban areas with precise street addresses but with many multiple-unit buildings present different problems from those in rural areas, where addresses may not provide geographic precision. This heterogeneity requires methods for identifying areas that require different kinds of attention and then targeted approaches for dealing with the different circumstances. Third, the magnitude of the task dictates automation almost everywhere. Input from other agencies will normally be in an automated, though not necessarily consistent, format. Flexibility in being able to accept and process different input formats is essential. Some manual entry of inputs or updates is inevitable. Fourth, the development of TIGER and MAF has to proceed in an integrated fashion. It is important to keep the linkages between the two databases current so that the products derived from them at any stage of the census process are consistent with each other. Fifth, the ability of local governments to provide accurate information in a timely manner varies enormously. Thus, plans for working with local governments need to be flexible and adaptable. With these general aspects in mind, we assess the Census Bureau's plans for TIGER and MAF.

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Preparing for the 2000 Census: Interim Report II CENSUS BUREAU PLANS The current Census Bureau plans, as we understand them, are set out in an unpublished document (Bureau of the Census, 1996b). Overall, we found this plan to reflect a sensible approach to the challenging yet crucial task of providing timely and high-quality TIGER and MAF databases for the 2000 census. As we elaborate below, our concerns center on the feasibility of achieving the plan's objectives in the face of budgetary and human resource constraints and on the procedures for dealing with those parts of the country for which up-to-date geographic and address representations will be difficult to create and maintain. The overall approach embraces three broad strategies. First, to the extent possible, it makes use of automated matching of files and updating of databases in the office, as opposed to field enumerations and checks. Second, it promotes the establishment of partnerships to achieve results. Third, it aims to make maximum use of inputs from USPS files, while taking account of any quality weaknesses, outdatedness, or inconsistency in those files across the entire country. Use of USPS Address Lists At the core of any updating strategy for a national address file, there has to be a nationwide source of current addresses. While the strategy of cooperative updating programs with local governments is essential, their coverage can never be complete and sufficient, and updating processes need to be developed for areas where no local contributions are available. With or without local cooperation, it is necessary to have some nationwide source of updating to ensure at least a minimum consistent level of quality across the country. The USPS provides a nationwide source of addresses that is frequently updated, by its Delivery Sequence File (DSF). However, it is not a panacea. For example, there may be time delays in making updates, unevenness of quality across carrier routes, rural addresses that may not reveal precise geographic locations,2 and addresses that do not have mail delivery that do not appear on the list. In addition, the 1995 test clearly revealed problems with the classification of vacant units on the DSF (Green and Vazquez, 1996). Nevertheless, it still represents the most valuable source of new addresses for the entire country. The Census Bureau is working appropriately to evaluate and understand the properties of this file and to incorporate it as a central component of the MAF updating process. The Census Bureau plan calls for using DSF three or four times each year to update the MAF. The plan ensures that an update using DSF occurs immediately before each major use of the MAF to produce address lists, for independent reviews, for survey frames, or for census mail-outs. Clearly the quality of MAF will be highly dependent on the quality of the DSF. During the 1995 census test, the Census Bureau found that 2   Although this has begun to change, it is clear that this process is not happening fast enough to seriously affect the 2000 census procedure.

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Preparing for the 2000 Census: Interim Report II updating the MAF with the DSF improved the deliverability of addresses (Corteville, 1996). However, as a rule of thumb, the USPS flags an address as vacant only if it is unoccupied for at least 90 days, so even a very late match to the DSF may not provide a comparable substitute for a manual "census address check" operation conducted by the USPS. Many of the other elements of the MAF updating strategy are designed to supplement the DSF contribution to MAF and to compensate for its weaknesses. Updating TIGER, MAF, and the Linkage Between Them Two programs are addressing the issue of TIGER updates and the linkage of TIGER to MAF. In February 1995 the Census Bureau began an operation called Master Address File Geocoding Office Resolution (MAFGOR) that aims to resolve discrepancies between address range information in TIGER and the individual addresses in MAF. Addresses in MAF that cannot be assigned to an address range in TIGER are resolved using address reference files obtained by regional offices or by information supplied by participants in the second updating program, the TIGER Improvement Program (TIP). As a result of this reconciliation, corrections are made either to TIGER or to MAF so that the problem addresses can be matched in any subsequent geocoding operations. Although originally scheduled for completion in 1998, MAFGOR will now be extended through the 2000 census due to the large number of addresses that are not geocoded. TIP is a partnership program under which local governments are invited to provide the Census Bureau with geographic files and other materials that can be used to update TIGER. TIP began in June 1995 and is intended to be an ongoing program. The MAFGOR/TIP operations have three critical stages. The first stage ends with the production of the maps and lists needed for the local update check of addresses (LUCA) program that provides local governments with a final precensus opportunity to review the Census Bureau's address lists and suggest changes (see below). The second stage adds subsequent improvements, from the LUCA program or elsewhere, to produce the MAF that will be used for the 2000 census mail-out. The third stage adds later arriving changes that can be used for supplemental mail-outs or enumerations. A third program, the Program for Address List Supplementation (PALS), is another partnership program that invites local governments to supply the Census Bureau with their address lists for matching with, and updating of, MAF. Address standards have been specified in the Federal Register, and software for matching lists has been developed. Invitations were sent out in summer 1996, and files provided in response to the invitation are to be verified against the standards and then matched to MAF and TIGER. The Census Bureau intends to feed back information on the disposition of all addresses submitted. For addresses that cannot be matched to TIGER, location information will be sought. All these programs implement the partnership approach with local governments that was advocated by Congress (Bureau of the Census, 1996). But there are potential problems. If the response by local governments is very high, the Census Bureau's resources may be taxed in trying to respond to all submissions, and failure to respond would probably create public relations problems. Yet a very low response rate by local

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Preparing for the 2000 Census: Interim Report II governments would put more burden on the other approaches necessary for updating the geographic databases. At this time the panel does not have the information to judge whether the resources available to the Census Bureau for these programs are sufficient for the work. Recommendation: The Census Bureau should develop a cost-benefit model for the planned MAF-TIGER updating processes to allow analysis and monitoring of its quality and to assess budgetary implications of different levels of participation or investment in those processes. Targeted Updating An important change of strategy from the 1990 census relates to what used to be known as the precanvass check. Prior to the census mail-out, the Census Bureau used to conduct a complete (100%) check of the address list (which in previous censuses had been based primarily on commercial sources). With the new approach to address list updating through MAF, this complete check is being replaced with a series of targeted checks at various points in the evolution of the MAF. For example, targeted checks are planned for multiple-unit buildings where there is a street address match between the DSF and the MAF but a significant difference in the number of individual dwelling units indicated at the address. A second targeted check is planned in areas with high potential for structure conversions from single-unit structures to multiple-unit structures. The LUCA program reviews can also be thought of as targeted checks. A key targeted check is planned for January 2000 and involves a USPS check of MAF addresses in areas with substantial housing growth. This check would identify addresses to which USPS is delivering mail but that do not appear on the MAF. The goal of this check is to compensate for the time lag in the DSF by identifying new construction (since mid-1999). The strategy of devoting resources to areas where the quality of MAF is thought to be deficient, rather than conducting blanket checks that make little difference in many areas, is clearly sensible if one is able to predict accurately where those deficient areas are. While the various targeted checks planned in the MAF-TIGER updating program focus on the obvious problem areas, the panel has not yet seen a plan for or demonstration of effective criteria for identifying specific kinds of problems. Recommendation: The Census Bureau should develop and make explicit the criteria it will use to determine which areas to include in each of its targeted updating checks. Rural Areas Rural areas present a particular problem of address list maintenance because the mailing address of a housing unit frequently does not reveal its precise geographic

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Preparing for the 2000 Census: Interim Report II location. The Census Bureau plans to construct a comprehensive list of rural housing units through a canvassing operation in the first quarter of 1998. This operation will identify the physical location of each dwelling unit on a map. It is timed to feed into the use of MAF for the continuous measurement survey program (the American Community Survey) later in 1998. These address lists may be subsequently updated through PALS or LUCA. The updated versions will then be used as the basis for an ''update/leave" operation immediately before census day. Address lists and maps will be updated and questionnaires left for return by mail. With the trend of extending the use of city-style addresses into rural areas, it may be possible to convert some rural areas to the mail-out part of the MAF before the census. Cooperation with Local Governments: Final Stages As described above, Census Bureau plans invite broad local government participation on a continuing basis in the updating and preparation of the geographic framework and address list for the 2000 census. These partnership programs supplement the regular updates through the DSF, as well as some of the targeted checks that the Census Bureau will be conducting. Local government involvement in the preparation of MAF culminates in the LUCA program, which provides a last opportunity for local governments to review the census address list and point out any needed additions, deletions, or changes. The Census Bureau would then review the suggested changes and update MAF as necessary. For those local governments that choose to participate in TIP or PALS, the LUCA program can be seen as the final confirmation stage of a continuing process. For those that did not participate, it is the chance to provide input into one of the prime determinants of the quality of the 2000 census. As a result of testing the LUCA program in the 1995 census test (Moohn, 1995a, 1995b; Barrett, 1995), several changes in the approach have been incorporated into the Census Bureau plans for 2000, focusing primarily on timing and communication. There are three key constraints on the timing of LUCA. First, the MAF that is supplied for local government review should be as accurate and up to date as possible. It would be wasteful to have local governments pointing out omissions that the Census Bureau would have found later; it would be better if local governments concentrated their effort on those areas where it is difficult for the Census Bureau to obtain good information. Also, sending a clearly deficient MAF to local governments may undermine the recipients' confidence in the census and leave the impression that the Census Bureau is not doing its job. The second constraint is to leave the local governments sufficient time to conduct their reviews thoroughly, given their resource constraints. To give them too little time is to belittle the importance of their contribution. Third, there must be sufficient time after receipt of the suggested changes for the Census Bureau to incorporate them, provide feedback, handle appeals, and update the MAF before the cutoff date for the census mail-out. These conflicting constraints have led to the following schedule: the materials for LUCA are to be prepared and distributed in January 1999; local governments review those materials and provide feedback in February and March 1999; and the Census

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Preparing for the 2000 Census: Interim Report II Bureau assesses the proposed changes and provides feedback to local governments in March-June 1999, in time for the cutoff date of July 1999 for preparing the main census mail-out. This is a tight schedule. While it may represent a reasonable compromise between the conflicting time constraints, many local governments may not have the time, expertise, or resources to do more than a perfunctory check of the address list. Ultimately, the effectiveness of the LUCA program depends on the rate of participation by local governments and the extent and quality of the changes they propose. The tight schedule leads to the risks that the Census Bureau will not receive the information they need from local governments, will not be able to incorporate the information, or will not be able to provide the promised feedback on the proposed changes within the time available in the census preparation schedule. These risks should be reflected in the content of the Census Bureau's communications with local governments so as not to raise expectations that cannot be met. In fact, a well-planned communication program with local governments on LUCA will be crucial to its success. The communication plan should cover at least the following elements:   the importance to local governments of a high-quality census, given its effects on revenue distribution, local planning, and redistricting;   adequate advance warning of upcoming activities, time constraints, the nature of the work expected of local governments, and the process of review, feedback, and appeal;   a clear explanation of the potential impact of the local government's input on the quality and cost of the 2000 census, including, for example, the negative impact of either not checking the lists thoroughly in the expectation that the gaps will get fixed during a census enumeration, or flooding the Census Bureau with doubtful addresses in the mistaken belief that this strategy will maximize the area's eventual census count;   emphasis on the fact that LUCA supersedes the former local review of the pre census address list--in other words, local governments will not get another chance after LUCA to review dwelling counts; and   how much flexibility the Census Bureau has in accommodating different formats of input and output in sending and receiving materials. To the extent that the Census Bureau is aware of particular weaknesses in the MAF extract it is sending to a local government, it should point out where the local authority might concentrate its review effort. Recommendation: The Census Bureau should develop a communication plan for its contacts with local governments on the LUCA program, emphasizing the importance of this program to a high-quality census and the implications of their participation in it. The Census Bureau should invite the active participation of all state agencies that are members of the Federal-State Cooperative Program for Population Estimates. These agencies can help the Census Bureau contact the appropriate people in local government

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Preparing for the 2000 Census: Interim Report II and help to publicize and encourage participation in the various stages of the local review process. Although not directly related to MAF, a potentially serious communications issue with local governments concerns the plan not to offer local governments a chance to review the final census dwelling counts. While we recognize that offering local governments the opportunity to participate in the updating of the address lists throughout the preparation of the census is a much more constructive approach, we are concerned that the abandonment of a post census local review of the type conducted in 1990 may be seen in isolation as the removal of an appeal right with potential financial implications for local areas. It is most important to ensure that local areas realize that LUCA has replaced this local review and are persuaded of the benefits of this change. Multiple Unit Structures As noted above, multiple-unit structures represent a problem in the updating of MAF due to ambiguity in the delineation of labeling of units within the structure. These structures are also a problem for nonresponse follow-up and integrated coverage measurement operations, which depend on clear identification of the individual units chosen for follow-up or reinterview. There seem to be three kinds of cases in a multiple-unit structure, each requiring a different approach in the census: units that are easily distinguishable and well labeled: these typically occur in modern apartment buildings and present no problems beyond those experienced in covering single-unit structures; units easily distinguishable, but without clear or unique labels (e.g., basement, ground, upper, or A, B, C): sensible rules are needed for deducing equivalency, with more emphasis being put on labels that incorporate physical descriptions (e.g., which floor, front or back); units that are not clearly distinguishable: different visitors to the same structure might count different numbers of units; in some cases the residents may not make the distinctions that the Census Bureau is trying to impose. Both the LUCA program and field checks should pay special attention to structures in the latter two categories. The inclusion in the targeted check of multiple unit buildings that are treated as a single drop for mail delivery purposes, as identified in the DSF, should help to clarify the MAF for many structures in the last two categories. However, there will inevitably remain structures for which unambiguous units cannot be delineated. In these cases, it might even be in the best interests of census coverage to treat the whole structure as the "dwelling unit" for the purposes of MAF, nonresponse follow-up, and integrated coverage measurement, in order to get all the people properly covered. That would imply the flagging of such addresses on the MAF, their omission from the mail-out, and the use of an update-leave or a list-enumerate procedure, where "list" means listing the units within the basic street address. Any subsequent nonresponse follow-up and integrated coverage measurement operations involving the address would

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Preparing for the 2000 Census: Interim Report II also be applied to the whole structure. Thus, if any forms were not returned by mail from this structure, the structure would be treated as a single sampling unit for nonresponse follow-up. Though this would represent a significant change from current plans and some added initial cost, it is a change that might alleviate a substantial source of cost, confusion, and complexity in subsequent enumeration and estimation operations. It merits consideration in the context of enumeration approaches for difficult-to-enumerate urban areas. ASSESSMENT The development of a comprehensive, accurate, and timely address list linked to the TIGER system is critical to the success of the 2000 census. This operation is the cornerstone of the entire census process. It is the foundation on which the implementation of the 2000 census methodology rests. Through the TIPS, PALS, and LUCA programs, the TIGER and MAF are reviewed by local governments prior to the census. Local governments' assessment of the completeness and accuracy of these databases will, at a minimum, affect their perception of how good a census the Census Bureau can conduct. The MAF then serves as the basis for the mail-out of the census questionnaires. The success of the mail delivery of questionnaires will affect local government, public, and media perceptions of the orderliness of the census process. The success of the subsequent "Be Counted," nonresponse follow-up, and integrated coverage measurement procedures is constrained by the quality of the address list and its geographic referencing to the correct census tabulation blocks. Finally, the published census counts and statistical data for small areas are dependent on completed questionnaires and sampled nonresponse follow-up forms being referenced to the correct geographic areas. In addition to enhancing the TIGER database and integrating it more fully with the MAF, the Census Bureau's plans for improving the quality of the address list are based primarily on input from USPS, and local governments and on targeted field checks. These may be supplemented, in ways not yet clearly defined, by information from commercial lists and from administrative records. While we agree with the general strategy being followed by the Census Bureau, we remain concerned about whether the resources available are adequate for the work to be done, at a high level of quality. We recognize that each of the primary updating sources--the USPS files and local governments--has weaknesses and that a program of targeted checking aims to address these weaknesses. The impact that private commercial lists will have on the quality of the MAF is still unknown because the solicitation of such lists took place only at the end of 1996. The panel has not seen any estimates of the expected quality of the address list after updates from these sources and therefore of the extent of dependence on targeted checking for the completeness of the final list. We are concerned about how precisely, and on the basis of what information, areas to be targeted can be identified. In the absence of a complete but expensive pre census field check, the success of targeting becomes a critical determinant of the quality of the MAF. The Census Bureau has not provided a cost-quality tradeoff analysis that

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Preparing for the 2000 Census: Interim Report II demonstrates that the proposed updating strategy, coupled with targeted pre census checking, would perform better than an approach incorporating a final universal pre census field check. In the absence of such an analysis, it might be wiser to reverse the burden of proof and develop criteria for exempting from an otherwise universal pre census check those areas for which an acceptably high level of accuracy from the updating processes can be confirmed. This approach would put the onus on demonstrating accuracy, rather than on spotting inaccuracy. Since developing an accurate MAF is the first step in taking the census, we reiterate its critical role in the decennial census. Recommendation: The Census Bureau should develop and maintain on the MAF a system of quality indicators at or below the census tract level and should use these indicators as a means of identifying areas requiring special pre census field checking to bring them up to an acceptable level of quality.