universe of indall files in BHPS UKHLS
Hi, I have a question on the universe of indall files. To investigate the reason for sample attrition, I have merged interview outcome code (ivfio) in indall file with pooled inresp longitudinal file. I have found quite many people who have appeared in the indresp file in the past, do not show up in the future indall file. I have expected them to appear in indall file with information on non-interview reason but many of them simply did not appear. To investigate whether these people were not original sample member of the study, I have looked into sample status variable (sampst) as well. However, many original sample members did not appear in indall file even though they interviewed in the past, and some of them return again to participate in interview after not showing up in indall file and indresp file for a few waves.
Could you please explain why indall file does not capture every sample member of the study?