Michael McCulloch wrote:
I am merging two datasets, KP.dta and PS.dta, which were sorted by
the variable <id>. They contain the subjects who from two different
exposure groups.
Values for <id> are unique to each dataset, so that <id> occurs only
once in each dataset, and are not duplicated across datasets.
Before the merge,
In dataset KP, one variable <smoker> has values yes or no: 1/0.
In dataset PS, <smoker> is missing.
However, after the merge, PS now has values for <smoker>.
I merged using this command:
use "A.dta", clear
merge using "B.dta"
Then, checked my data:
id group smoker
1 PS 1
2 PS 1
3 PS 1
4 PS 0
5 PS 0
6 PS 1
7 PS 1
8 PS 1
What have I done wrong?
------------------------------------------------------
Are you sure you don't want to -append- rather than -merge-.
If you want to merge on id, write:
merge id using "B.dta"
Hope this helps
Svend
__________________________________________
Svend Juul
Institut for Folkesundhed, Afdeling for Epidemiologi
(Institute of Public Health, Department of Epidemiology)
Vennelyst Boulevard 6
DK-8000 Aarhus C, Denmark
Phone: +45 8942 6090
Home: +45 8693 7796
Email: [email protected]
__________________________________________
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