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 and ESRs for the 1980 and 1990 censuses as a result of apparent user disinterest in this information.

Finally, the Census Bureau uses one other approach that combines counties. This county grouping is of the Census Bureau’s public-use microdata samples (PUMS). The PUMS data product differs from the standard printed reports, computer tapes, microfiche, and the like, that present statistical summaries of all responses, either of complete-count information or of information collected from only a sample of households. By contrast, the PUMS files use a sample of raw data for areas of 100,000 or greater population; PUMS areas typically comprise large cities, groupings of counties, or remainders of counties. From these samples, the data users can select and manipulate specific responses to create customized decennial census tabulations in much the same way as if they had collected the information in their own census or sample survey. Strictly speaking, the PUMS microdata areas are not official geographic units, as the Census Bureau provides neither totals nor summary information for them. Instead, they are part of an ad hoc geographic framework established for data users who wish to analyze the diverse relationships among responses to standard questions.

As geographic combinations, the regions and divisions are familiar within the data user community. The Census Bureau intends to continue preparing data tabulations for these entities as standard parts of its tabulation and publication programs in future decennial censuses of population and housing, its quinquennial agricultural and economic censuses, its many current sample surveys, and its other compilations and compendia. As part of its continuing effort to improve the definition and delineation of geographic areas for each decennial census, the Census Bureau’s Statistical Areas Committee will review the components of the regions and divisions to ensure that they continue to represent the most useful combinations of States and State equivalents. 6-22Statistical Groupings