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PUMS & PUMAs
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|Public Use Microdata Samples
Public Use Microdata Sample (PUMS) data is based on individual census records and is available only at large geographic areas. Think of the PUMS dataset as the raw, disaggregate census sample data, at a large enough geographic level necessary to protect the confidentiality of the census respondent. With the decennial census there are two PUMS data files:
layout for the 1-percent PUMS file is available on the Census
Bureau's web site.
Public Use Microdata Areas (PUMA)
The PUMS data is released at geographic areas called Public Use Microdata Areas, or PUMAs. The minimum size threshhold for the 5-percent PUMAs is 100,000 persons, and the minimum size threshhold for the 1-percent "super-PUMAs" is 400,000 persons.
PUMAs were defined by the State Data Centers in cooperation with Regional Data Centers and Affiliate Data Centers. This PUMA delineation process was completed in spring 2001, and are based on Census 2000 population counts from the PL 94-171 databases. Details of the PUMA delineation process are outlined in an April 2001 letter from the Census Bureau to the SDCs (PDF file). In addition, USDOT staff prepared a guidance paper on defining PUMAs for transportation planning purposes (PDF file).
The boundaries of the 5-percent PUMAs are included in the currently available 2001 version of the Census TIGER/Line files. Boundaries for the 1-percent PUMAs will be included in the 2002 version of TIGER/Line. For more information on PUMAs within TIGER, visit the Bureau's TIGER site at: www.census.gov/geo/www/tiger/.
For more information on the decennial
census PUMS program, visit the Census Bureau's PUMS 2000 page at: http://www.census.gov/population/www/cen2000/pums.html.