lishing selected multiyear averages in nominal dollars as well as inflation-adjusted dollars.

4-D.4
Tabulation Specifications

The long-standing release plan for tabulations from the ACS includes two major elements: (1) the universe or population covered and (2) the geographic areas for which tabulations are produced. The full universe for ACS data products, beginning in 2006, will include the housing unit and GQ populations, although some tables may be published for subuniverses, such as households or the noninstitutional population. (Prior to 2006, tabulations included just the housing unit population.) For geographic areas, the available products (1-year, 3-year, and 5-year period estimates) will depend on the population size of the geographic area (refer back to Tables 2-4 and 2-5).

The Census Bureau will need to follow its plan for a number of years, not only to allow time for collection of sufficient data to begin release of 3-year period estimates in 2008 and 5-year period estimates in 2010, but also to allow both the Census Bureau and the data user community sufficient opportunity to gain experience with the various sets of tabulations. Yet the Census Bureau should not neglect to consult with users to determine if the population universe and the geographic area specifications are optimal or might be modified to produce more useful information.

With regard to population coverage, the key question is the role of GQ residents, particularly those in institutions. The Census Bureau will need to consult with users regarding appropriate universe definitions for ACS tabulations—for example, employment and income tabulations may be most useful if they are restricted to the noninstitutional population. In 2000, confidentiality concerns sometimes precluded the publication of the same tabulations separately for households and GQ residents in very small areas. Because the ACS estimates for small areas are averages over multiyear periods, confidentiality concerns could be less of a problem in this regard. Ideally, consultation with users on the most useful tabulation universes would precede and feed into the production of tables for 2006 (for release in summer 2007), which will be the first year to include GQ residents.

For the geographic area release schedule, one issue is the population size cutoff for publication of 1-year period estimates, for which the Census Bureau might consider the usefulness of lowering the current threshold of 65,000 residents to one of, say, 50,000 residents. The discussions in Chapters 2 and 3 emphasize the large sampling errors of 1-year period estimates for a small population group (such as school-age children in poverty) for geographic areas with fewer than 250,000 people, so lowering the threshold might appear to be deleterious. However, estimates for major population



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement