I am working with some data in Larrimore et al. (2008, JESM) to address topcoding of the income data in the CPS. Based on discussions with the authors they use 4 components of labor earnings starting in 1988: primary earnings from any source (farm, wages, or self-employment) secondary wage earnings, secondary self-employment earnings, and secondary farm earnings. It would appear that these series have already been combined in the IPUMS data (INCFARM INCWAGE INCBUS). IS there any way to back out the original series? Apparently the 4 category version of the data are available from the NBER and Census CPS sites. I have already done an immense amount of work on this project using the IPUMS data so would prefer not to have to switch things around.
THanks for your help.