I’m seeing some small differences in the HRHHID variable in 1976-77 between IPUMS and the NBER files, do you know why this might be happening?
For example, in January 1976, the two individuals in the sample with HUHHNUM = 8 have HRHHID = 167004034020 in IPUMS and HRHHID = 167004034051 in the NBER file (difference in bold). This type of problem seems to be affecting almost all observations in 1976-77. Usually the problem is with the final two digits, but not always.
This problem came up when trying to match the NBER files to IPUMS. I’m matching on HRHHID, HUHHNUM, and LINENO, which matches almost all observations for 1978 onwards.