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Differences between the Income and Poverty Estimates from the American Community Survey and the Annual Social and Economic Supplement to the Current Population Survey
August 28, 2007
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:
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American Community Survey |
Current Population Survey |
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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. |
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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. |
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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. |
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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. |
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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. |
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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).
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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). |
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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. |
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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. |
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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. |
