Annual Social and Economic Supplement (ASEC) to the Current Population Survey (CPS) CPS homepage
Because of its detailed questionnaire, the CPS ASEC is the primary source of timely official national estimates of poverty levels and rates and of widely used estimates of household income and individual earnings, as well as the distribution of that income.
The CPS ASEC provides a consistent historical income time series, beginning in 1946, at the national level, and can also be used to look at state-level trends and differences (through multi-year averages) going back to 1984. However, the relatively large sampling errors of state-level estimates for smaller states somewhat limit their usefulness. (Background on CPS ASEC)
American Community Survey (ACS) ACS homepage
Starting with 2000, the ACS provides subnational estimates of income and poverty for the nation, states, and places, counties, and metropolitan areas with a population of at least 250,000. The sample size of this survey from 2000 to 2004 was about 800,000 addresses per year.
In 2006, the ACS began releasing annual subnational estimates of income and poverty for all places, counties, and metropolitan areas with a population of at least 65,000 as well as the nation and the states. The sample size of this survey increased to about three million addresses per year, making the ACS exceptionally useful for subnational analyses. Three-year averages are available starting in 2008 for areas and subpopulations as small as 20,000. Five-year averages will be available for census tracts/block groups and for small subgroups of the population starting in 2010. All ACS estimates will be updated every year after they are first available. Because of its large sample size, estimates from the fully implemented ACS provide the best survey-based state level income and poverty estimates. (Background on ACS) The ACS estimates have a different reference period than the CPS ASEC and a different population universe.
Survey of Income and Program Participation (SIPP) SIPP homepage
The SIPP is useful mainly for understanding changes for the same households in income and poverty, that is the dynamics of income and poverty, over time (up to 3 or 4 years), and for examining the nature and frequency of poverty spells. The SIPP also permits researchers to look at monthly or quarterly changes in income and poverty and periods of income receipt of less than a year. (Background on SIPP)
Census 2000 long form
The best measure of change between 1990 and 2000 for subnational areas, even small places, and for subpopulations, are the comparisons of Census 2000 results with those from the 1990 Census long form. Since the ACS replaces the long form, the 2010 census will not include a long form and will not provide income and poverty estimates. ACS estimates can be compared to Census 1990 and Census 2000 estimates. When released in 2010, ACS five-year estimates for small areas will provide data at the census track level which will be comparable to earlier decennial census estimates. (Background on Census 2000 long form)
Small Area Income and Poverty Estimates (SAIPE) program SAIPE homepage
The SAIPE program produces single-year estimates of median household income and poverty for states and all counties, as well as population and poverty estimates for school districts. Since SAIPE estimates combine ACS data with administrative and other data, SAIPE estimates generally have lower variance than ACS estimates but are released later because they incorporate ACS data in the models. For counties and school districts, particularly those with populations below 65,000, the SAIPE program provides the most accurate subnational estimates of poverty. For counties, SAIPE generally provides the best single year estimates of median household income. (Background on SAIPE)