Merge keep(match)

[Anne-Claire Jo]

Hello all,

I am a bit lost with merging two datasets.
I tried to merge two data and keep only the observations that are matched in the master data (1:m).
Therefore, I used:
merge 1:m id using "using_data", keep(match)

I want to double-check if this code is identical as (or what I intended to do):
merge 1:m id using "using_data"
keep if _m == 3

Thanks a lot !

[Clyde Schechter]

Yes, those are the same.

And they will retain all and only those observations where id appears in both data sets. So unmatched observations from either data set will be excluded from the result.

[Anne-Claire Jo]

thanks for your reply ! it's clear now