Where can I find a crosswalk between IPUMS OCC and NHIS OCCUPN1? OCCUPN2 would also be helpful.
The appendix of this document shows how the coding scheme of the OCC variable found in IPUMS Health Surveys is re-coded into the two-digit OCCUPN. The sub-categories correspond to OCCUPN1 and the general categories correspond to OCCUPN2.
I hope this helps.