How to drop entire observations with duplicates for a particular variable keeping the original (or the first observation

[anisha arya]

I have data from a survey where some participants opened the survey twice, thrice or more. How do I drop the data for the second and onwards entries regardless of whether they completed the survey or not at a go for any entry. I want to only keep the first observation. These participants are identified by the ID number, var(id). So

id	surveyprogress%
1	23
1	12
1	56
2	13

In this case, I would want to drop the third and fourth rows because the share the same ID number as row 1.

Please let me know, thank so much in advance!

[Clyde Schechter]

Assuming the dataset is already sorted in the correct order so that the chronologically first observation is also the physically first one, it's easy:

sort id, stable
by id: keep if _n == 1