Dear stata members,

I am trying to loop over multiple files (rounds) of data. In the first two rounds of data, there are only 2 wage variables. However, in the later rounds there are 5 wage variables. Even when I generate the 3 wage variables that are missing in rounds 1 and 2 in those rounds using a unique round_ID, I get the error that those variables are already defined. What command do I add into the loop to tell stata to either skip over these variables in the first two rounds or generate the variables such that it doesn't give me an error later?

Thanks in advance.

Best,
Janaki