how to only keep the observation at inclusion in a dataset

[marguerite briand]

Hi,

I m using STAT V17

I have a dataset where observation at inclusion are mixed with follow up observation..
I have the "date of inclusion" and "date of mesurement" for the observation
And I only want to use the inclusion data ..

I wonder if there is a way for an observation with the same "ident" to keep only the observation with the earliest measurement date ?

here and exemple of the dataset:

Thank you for your help !

Marguerite

[Carlo Lazzaro]

Marguerite:
you may want to try what follows (caveat emptor: code untested due to the lack of a viable example provided by the original poster, despite the FAQ recommendations ):

bysort ident (Date_of_mesuremen): keep if _n==1

[marguerite briand]

Thank you for your answer, it was really helpfull,
This solution perfectly work
I take note for the FAQ recommendations !

Marguerite