In regard to EDSUPPWT, something is amiss for the years 1989 to 1993. The weight needs to be multiplied by 100 to get accurate population counts. Thanks.
You are correct that there is an error in the EDSUPPWT variable. I have alerted the IPUMS CPS team and they are working to fix this variable. In the meantime, I suggest using WTFINL instead of EDSUPPWT for years prior to 1994. Please be aware that the universe of this variable is different for years 1990-1992 and 1976-1977, so the weight will need to be set to zero for the NIU individuals for those years.
Thanks for catching this error. We like to reward users who bring errors such as this to our attention with an IPUMS coffee mug. Please send an email to ipums@umn.edu to claim yours.
The IPUMS CPS team has fixed this problem and will be releasing a new version of the database at the end of this week. Although I previously recommended that you should use WTFINL prior to 1994, this is not quite correct. You should wait for the new version of the database with fixed weights.
EDSUPPWT has now been fixed and the new data can be downloaded on the IPUMS CPS website.