Summary: The Congress asked GAO to review operational and programmatic aspects of the Census Bureau's ACS that will affect the reliability of small geographic area data. The ACS will be a mail survey of about 3 million households annually, whose results will be cumulated over 5 years to produce estimates that will replace information previously provided by the Decennial Census long form. In addition, annual data will be published for geographic areas with 65,000+ populations and as 3-year averages for areas with populations of 20,000 to 65,000. Annual data will be published beginning in 2006 with data for 2005. The 5-year averages for 2008-12 will provide data for small geographic areas.
The Census Bureau's development of the American Community Survey goes back several decades and has included intensive research and field testing programs, as well as substantial outreach efforts, in particular through the reports and workshops at the National Academy of Sciences (NAS). However, if the ACS is to be an adequate replacement for the Decennial Census long form as the major source of data on small geographic areas and if it is to provide similar annual data for larger areas, the Census Bureau will need to incorporate in a timely manner the resolution of issues it has already identified in the ACS testing and 2000 Decennial Census evaluation programs, such as the residence concept, group quarters, and questions on disability; complete the ACS testing plan as originally planned, such as the comparison and evaluation of long form-ACS supplementary survey data at the state level, to identify other unresolved issues and to provide information for users of 2000 Decennial Census long-form data that will be necessary for the transition to the full ACS; evaluate and consult with stakeholders and users on the resolution of issues identified in this report, such as the methodology for deriving population and housing controls, guidance for users on the impact of the characteristics of multiyear averages for small geographic areas, and the presentation of dollar-denominated values; coordinate the results of the testing program for the 2010 Decennial Census short form with the ACS implementation schedule; and resolve all issues so that the ACS estimates beginning with 2008 are consistent with the ACS estimates for 2009-12 and with the 2010 Census short form. Although the Census Bureau has solicited advice from external stakeholders and users and has supported research by its own staff on most of the issues identified in this report, there is no indication that the Census Bureau has yet followed this advice or implemented plans for consultation on resolving these issues. In addition, it has been more than a year since the Census Bureau announced that it was looking into establishing an ACS partnership program that would involve advisory groups and expert panels to improve the program, but no such program has been established. Another issue related to the proposed ACS is how the Census Bureau might provide more timely and reliable small geographic area data. This goal could be accomplished, but it would require additional funding. The most direct approach would be to increase the sample size for 2009-11. This increase would enable the Bureau to provide small geographic area data that would be the replacement for the 2010 Census long form 1 year earlier.
