March 2001: User Note

The Census Bureau is revising estimates derived from the Current Population Survey March 2001 supplement data file due to the discovery of a weighting error. National estimates of median and mean income, poverty rates, and health insurance coverage were only minimally affected (see Table below). The error resulted in the assignment of incorrect weights to records in the March 2001 supplement file. Weights for adults (age 16 years and older) were only minimally affected. The impact was primarily on the weights for children (under the age of 16) and varied by state, thus, sub-national estimates of children's data are most likely to show a change when using corrected weights. However, since the weighting problem affected all records on a proportional basis, ratio estimates and percent distributions should show only minor changes, even those for children.

For users who have already obtained a copy of the file, corrected copies of the public use file and an extract file containing just the corrected weights will be available through Customer Services Branch on December 4. Contact them through normal channels to obtain a copy of either. Additionally, the FTP file has been corrected and will be available December 4.

http://www.bls.census.gov/ferretftp.htm#cpsmarch

The extract file will be available over the Internet on December 1, at the following address:

www.census.gov/ftp/pub/housing under the file name: MAR2001WGTS.DAT

A document providing the layout for this file and appropriate match procedures is found in the same directory, file name: REVWGT.TXT

On December 4, we will correct the file available through FERRET. The tables available through FERRET and the Bureau's Homepage are being revised and will be updated on a flow basis between now and the end of the year.

Table 1: Effect of Weighting Error on income, poverty, and health insurance estimates: 2000

Annual Demographic Survey (March CPS Supplement) 2001 Public Use File Page

CPS Main Page