st: Expanding single observation data to create unbalanced panel data set-up

[Geoffrey Wallace <gw46@cornell.edu>]

I have a civil war data set that contains a single observation for each 
war, including start year, end year, and other conflict-level variables 
for all wars that were ongoing or began between 1988 and 2004. My 
objective is to expand this data set into a panel format with separate 
annual observations for both the war and post-war periods, while all 
years before the war started are excluded. So for a war lasting 
1990-1992, this means there would be no observations for 1988-1989, but 
then observations for the war years 1990-1992 as well as postwar years 
1993-2004.

A complicating factor is that some countries experience several separate 
wars during this period, each of which has a unique id. I want to make 
sure I don’t create duplicate observations for those cases, but rather 
have a simple indicator variable with “1” when a country is experiencing 
war and “0” for the post-war period.

My question is whether anyone can suggest a relatively efficient way for 
producing such a data set.

I’ve thought of manually going through the data and including a variable 
indicating the number of years for the relevant war and post-war period, 
then using the –expand– command to create the larger data set, and then 
somehow reformatting it afterward for indicate each relevant year for 
the war and post-war periods. However, I was wondering if there was a 
more straightforward way to do this.

Thanks for your consideration.

Geoff

-
Geoffrey Wallace
PhD Candidate
Department of Government
214 White Hall
Cornell University
Ithaca, NY 14853
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