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st: Drop observations of groups with gaps in their data
From
Christopher Baum <[email protected]>
To
"[email protected]" <[email protected]>
Subject
st: Drop observations of groups with gaps in their data
Date
Fri, 3 Jun 2011 05:37:48 -0400
gvkey year
1001 1985
1001 1986
1001 1987
1001 1990
1001 1991
1200 1986
1200 1987
1200 1988
1200 1989
I want to drop all the firms that have a gap in reporting (gvkey = firm code). This means that all firms which e.g. reported from 1985 to 1987 and then again from 1990 to 1991 have to be dropped. Those companies should completely be eliminated from the data set, meaning stata should drop all observations of this company. So in the end I am left with the companies that do not have any gaps in reporting.
How about
bys gvkey: g dy = cond(_n==1, 1, year[_n]-year[_n-1])
egen tokill = max(dy), by(gvkey)
drop if tokill > 1
Kit Baum
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