Hi,
I am new to the list server, though have been using Stata for the last couple of years. So, please forgive me if I am not following any of your conventions in asking a question.
I want to do a pair wise comparison of several variables across different years. I would like to know how many new characters under P1 and P2 (together)exists in year 1996 that did not exists in year 1995.
The dataset looks like this:
Year P1 P2
-------- ------- ------
1995 A B
1995 A C
1995 D A
1995 E A
1996 B A
1996 A M
1996 A H
1996 A C
So the code should show "2", since character M and H exist under P1 and P2 in the year 1996, but not in 1995.
Thanks in advance,
Navid
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