I downloaded IPUMS CPS 70s and 80s samples. I selected Earner Studies variables (Outgoing Rotation Group). Those variables are not available for 1979 to 1981 IPUMS CPS samples while the NBER provides MORG files for those years (http://www.nber.org/morg/sources/arch…). Furthermore, some academic studies such as Balleer and Rens (2013) use the earner study variables starting from 1979.
Thus, are those variables absent from 1979 to 1981 IPUMS CPS samples due to inconsistencies in the raw data or work in progress or else?
The “missing” earner study variables in the 1979-1981 basic monthly samples is more a feature of ongoing work in progress for the IPUMS CPS team. The IPUMS CPS project is currently working toward making every CPS source variable available as reflected in the NBER files. This process, as you might expect, takes a bit of time to complete. In the meantime you can merge NBER CPS data with IPUMS CPS data using the information available here.