Merging ASEC and March Basic samples

Not sure if this is the right place to post, but I’m giving it a shot… I’m attempting to merge ASEC longitudinal files with March BMS files for the last few years. Is it the case an individual would have a different pernum value in the March BMS versus the ASEC? For some people, I have two records, with the first record reflecting their March BMS responses; and the second reflecting their ASEC responses. This isn’t the case for everyone in the merged file. Am I doing something wrong? If it is true that pernum may differ, how should one work around this? Thanks very much!

Not everyone in the ASEC will have a match in the March Basic sample, but everyone in the March Basic sample should have a match in the ASEC sample. The best way to merge these two files is using CPSIDP instead of PERNUM. Individuals in the ASEC that do not match to the March Basic will have CPSIDP. These individuals are in the ASEC oversample.