Regression of a few selected observations

[eunice tan]

I have a set of data but would only require to use of a few observations from the entire dataset. I was wondering if there is an easier way I can select the observations I want to be used in my regression than me keeping them one by one.

Thank you

[Carlo Lazzaro]

Eunice:
without any data example from your end, I'd recommend you an -if- clause or to take a look at the -group- function available from -egen-.