|Per Capita Income,
Earnings (people), and Income (people)
||Compare with Caution
The ACS collects data throughout the year on an on-going,
monthly basis and asks for a respondent's income over the "past 12 months." Census 2000,
however, collected the income data for a fixed period of time -- "during 1999" (the last
calendar year). For example, the 2007 ACS 1-year data reflect incomes over 2006-2007 and the 2005-2007 ACS 3-year data reflect incomes over 2004-2007. In a comparison study between Census 2000 income data and the 2000 ACS,
income collected in Census 2000 was found to be about 4 percent higher than that in the 2000
ACS. For more information on the differences of income in the ACS and Census 2000, see
Income in the American Community Survey:Comparison to Census 2000.
The Census Bureau recommends using CPI-U-RS adjustment factors published annually by the
Bureau of Labor Statistics (BLS) to adjust 1999 median, mean, and per capita income dollar
amounts shown in Summary File 3 to 2007 dollars by multiplying the 1999 dollar amounts by
the CPI-U-RS factor of 1.24438087. For CPI-U-RS inflation adjustment factors for other years
see: BLS Consumer Price Index.
Furthermore, direct comparisons of income and earnings distributions between Census 2000 and
the 2007 ACS are not possible due to inflation. Users interested in making distribution
comparisons need to inflation adjust individual income records using the Public Use
Microdata Samples (PUMS) files from Census 2000.
|Compare with Caution
As ACS data are collected every month of the year,
adjacent years will have some reference months in common. Hence, comparing the 2007 ACS
with the 2006 ACS estimates is not an exact comparison of the economic conditions in 2007
with those in 2006. For a discussion of this and related issues, see Hogan, Howard,
"Measuring Population Change Using the American Community Survey," Applied Demography in the
21st Century, Steven H. Murdock and David A. Swanson eds., Springer Netherlands, 2008.