Observations Do not Match Up NBER ASEC and IPUMS CPS ASEC for 2001 and 2014?


In theory, you should be able to merge the NBER March supplement and the IPUMS CPS supplement for every year. Moreover, I can merge them perfectly from 1988 to 2016 for all years except for 2001 and 2014.

I think it has something to do with special sampling in those two years in particular. In 2001, the CPS also had SCHIP supplement questions and in 2014 the CPS did an odd sampling in order to incorporate new income questions. Can someone confirm that these are the reasons the number of observations differ? If not, can someone explain why this only occures in these two years?



Your assumptions are correct. The 2001 ASEC file available through the IPUMS CPS extract system includes the SCHIP expansion (the NBER CPS Supplements page has the SCHIP file as a separate link for March 2001) and the 2014 ASEC file includes both the 5/8ths and 3/8ths samples while NBER offers them separately (labelled “traditional” and “redesign”), so these case count differences are expected.

I hope this helps.



Thank you very much for your help on this, and my other questions as well. I really appreciate you taking the time to look into these very specific questions for me! It has really helped me a lot with the research I am doing! Thanks again.