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Fact Sheet - Differences Between CPS ASEC and ACS

Differences between the Income and Poverty Estimates from the American Community Survey and the Annual Social and Economic Supplement to the Current Population Survey.

The American Community Survey (ACS) is currently the largest household survey in the United States. The ACS is part of the 2010 Decennial Census Program and will eliminate the need for a long-form sample questionnaire. The ACS offers broad, comprehensive information on social, economic, and housing data and is designed to provide this information at many levels of geography, particularly for local communities. With full implementation in 2005, the ACS is now producing annual estimates for geographic areas with populations of 65,000 or more. Beginning in 2008, the ACS will release data for geographic areas with populations between 20,000 and 64,999 using data collected over the three-year period 2005 to 2007. Beginning in 2010, the ACS will use five-year averages to provide estimates for all areas down to census tracts/block groups.

Because of its detailed questionnaire and its experienced interviewing staff, the Current Population Survey (CPS) Annual Social and Economic Supplement (ASEC) is a high quality source of information used to produce the official annual estimate of poverty, and estimates of a number of other socioeconomic and demographic characteristics, including income, health insurance coverage, school enrollment, marital status, and family structure.

The following chart summarizes the key differences between the ACS and the CPS:

American Community Survey Current Population Survey
Principal Purpose Part of the 2010 Decennial Program, providing annual (or multi-year average) estimates of selected social, economic, and housing characteristics of the population for many geographic areas and subpopulations. Produce specific socioeconomic and demographic estimates for the United States, and estimates for states for selected characteristics and subpopulations. Provide timely estimates of income and health insurance, as well as official poverty estimates.
Geography Nation, states, and cities and counties of 65,000 or more. Eventually, areas as small as census tracts using multi-year averages. Nation, regions, and states for selected characteristics.
Sample Size About 3 million addresses per year. Data are collected from about one-twelfth of the sample each month. Annual sample size is about 100,000 addresses.
Data Collection Method Mail, telephone, and personal-visit interviews for the 50 states, the District of Columbia, and Puerto Rico. (The Puerto Rico Community Survey began collecting data in 2005.) About half the responses are obtained by mail. The ACS is a mandatory survey. Telephone and personal-visit interviews for the 50 states and the District of Columbia. The CPS is a voluntary survey.
Residency Status The ACS includes a person at the address where they are at the time of the survey if they have been there, or will be there, more than 2 months, whether or not they have a “usual residence elsewhere.” The CPS sample unit’s householder (one of the people in whose name the unit is rented or owned) must consider the unit to be their place of usual residence (where they spend most of the time during the year) to be counted as an occupied unit, which is traditional in most censuses and housing surveys. If a family has more than one home, the interviewer has to determine if the sample unit is their usual residence.
Population Universe The 2005 ACS included only the household population. This universe includes both the civilian and military population in households and excludes the group quarters population. The group quarters population consists of the institutionalized (such as people in correctional institutions or nursing homes) and the noninstitutionalized (most of whom are in college dormitories). The ACS began a group quarters data collection effort in 2006 and released the first total population estimates in 2007. The weighting is controlled to population estimates as of July 1 (e.g., July 1, 2003 for the 2003 ACS). The CPS includes the civilian noninstitutionalized population. This universe includes civilians in households, people in noninstitutional group quarters (other than military barracks) and military in households living off post or with their families on post (as long as at least one household member is a civilian adult). The universe excludes other military in households and in group quarters (barracks), and people living in institutions. The weighting is controlled to population estimates as of March 1 (e.g., March 1, 2004 for the 2004 CPS ASEC).
Time Period Covered ACS collects data continuously thoroughout the year and the reference period for select questions (like income and the number of weeks worked) is the 12-month period prior to the resonse month. Therefore, people responding in January of 2005 reported income for January to December of 2004. People responding in December of 2005 reported income from December 2004 through November 2005. This yields a total time span covered by responses of 23 months. The survey’s 12-month estimates are centered on December 15, 2004. Monthly interviews conducted from February to April 2006 ask about calendar year 2005 income. The survey’s 12-month estimates are centered on July 1, 2005.
Length and Detail of Questions Using a series of eight questions, the ACS asks about money income, plus one type of noncash benefit (food stamps) during the previous 12 months. CPS asks a series of questions about more than 50 sources of income, including questions about the amount of several noncash benefits such as food stamps and employment-related health insurance, during the previous calendar year.
Inflation Adjustment All dollar values for income are adjusted to latest calendar year of estimates using the Consumer Price Index for the date collected versus the average for the year. None

Source: U.S. Census Bureau | Social, Economic, and Housing Statistics Division: Poverty |  Last Revised: September 16, 2014