Which was the first 1980 US Census 1% sample available on IPUMS USA, and has that sample been changed since 2001 by either changing which observations are in the sample or by adding in preiviously-missing data (not entirely new variables) for any obervations? I am trying to replicate results from a published paper, and there is a 1039-person difference in the sample sizes we end up with (which the author cannot explain).
Much of this information, if available, is documented on the revisions page. Specifically, the 1980 Labor market Areas sample and the 1980 Detailed Metro/Nonmetro sample were both released on November 23, 2004. It looks like the 1980 Metro sample and the 1980 Urban/rural sample were both available before that time. So it seems like the paper could have used either of these latter two samples. Since then there have been a number of changes and additions to variables within these samples. I’d suggest looking through these changes to verify if any of these fixes may be influencing your sample size.