The poverty universe is made up of persons for whom the Census Bureau can determine poverty status (either "in poverty" or "not in poverty"). The definition of poverty universe for SAIPE estimates is the same for 2006 and beyond and conceptually matches the poverty universe of the American Community Survey (ACS). The poverty universe estimates are not the same as the population estimates from the Census Bureau's Population Estimates Program. Instead, they are derived estimates that differ from population estimates in the following ways:

• Beginning with 2006, the poverty universe includes group quarters populations only for noninstitutionalized group quarters, not elsewhere classified. Residents of college dormitories, military housing, and all institutional group quarters populations are excluded.
• The poverty universe does not include children under the age of 15 who are not related to a reference person within the household by way of birth, marriage or adoption (for example, foster children). The reason is that Census Bureau surveys typically ask income questions only of persons age 15 or older and those under 15 related to a reference person within the household.

The poverty universes provided on this web site are the estimates used in the production of the SAIPE program's poverty rates for the given year and are not updated to reflect any successful challenges or other subsequent updates (annual or otherwise) to the published population estimates from the Population Estimates Program. Due to their method of construction, the poverty universe estimates are sometimes larger than the official population estimates. This happens partially because the age groups for the SAIPE program's poverty universe estimates do not in all cases match the age groups used as population controls in estimating the ACS.

The 2005 poverty universe estimates excluded all group quarters’ residents, matching the definition of the 2005 ACS.  Prior to the estimates for 2005, the poverty universe data were derived from the Annual Social and Economic Supplement of the Current Population Survey. Please see the denominators for model-based poverty rates webpage for details on how SAIPE poverty universes are produced.