Dear Stata users,

I will please like some explanation. I am working on the topic "the effect of childhood conditions on educational attainment in adult years". I have information from wave 1 of the data on childhood conditions as well as on some controls and information on educational attainment and other controls in wave 7. I need to combine these 2 waves for my analysis.
Upon combining i have my final sample.
Because i have a lot of missing data in wave 7 i consider comparing how the individuals in the baseline sample differ from individuals in wave 7 to see how attrition affected the generalizability of the sample.


My question is, how do i compare this final sample with the wave 1 using statistical tests when they are in different data files.

Many thanks.