Hi Everyone,

Thanks for taking the time to read my query.
I currently am cleaning a very big dataset (52 variables, 82284 observations) for longitudinal analysis. The dataset is based on information returned from 6 different surveys. I have converted the dataset to long format so currently there are about 6 different observations (in years) for each ID. There are approximately 13,000 unique ID variables.
In the third survey that was sent, additional information was asked that was not included in any further surveys but is essential to my analysis. I therefore want to exclude all participants who did not complete the third survey (in 2010).


What I am trying to find is some kind of command like this: drop id if Survey3Completed=. in 2001

Thank-you very much.
Sarah