I imported several csv files with "birthdate" as one of the variables into Stata and then I appended the files to produce one dataset. However, dates from some of the constituent datasets did not show up at all.

To solve this problem, I used the command "tostring birthdate" before appending The hitherto missing dates now show up but as figures, some positive, others negative.

I have tried various manipulations, but these dates do not convert to the actual birthdates from the csv files.

After formatting as dates, they mostly default to 1960 as the birth year. But that is not the birthday in the original file.

Please kindly help me solve this problem.