Hi everyone,

I'm currently having a long data set with the following structure:
case month birthyear
1 1 1951
1 2 1951
1 ... 1951
1 624 1951
2 1 1960
2 2 1960
2 ... 1960
2 624 1960
The case identifies one individual, I'm having 1250 cases in total.
Then the month counts from 1 to 624 for each individual. The month "1" for each individual is the December of the year, in which they turned 15. Meaning for case 1 month 1 would be December 1966.
I now want to create a new variable "calendar date" for each individual and each month that contains the actual month and year the "month" variable is referring to. Meaning the first "calendar date" for case 1 in month 1 should be 12/1966.

Could you please advise me in how to do this with a loop/condition or whatever is needed for all individuals?

Thank you very much!
Best regards
Marie