How to code which participants to use

[n1ojima]

I am pretty beginner so excuse me if this is a remedial question, I have tried googling the answer and haven't been able to find the answer.

I am working with survey data that has two waves. I want to only use the participants that answered the survey for both waves and throw out the ones who did not do the follow up. I have both waves merged into the same large set, so ideally what I want to do is delete out any of the participants in the first wave that do not have follow ups attached.

What is the best way to go about this?

[Kurt_Bremser]

Plesse post some example data (as text, not as pictures or Excel files, ideally in a DATA step with DATALINES), so we get a feel for the structure of your data.