st: data management help

[mnitkin <mnitkin@bu.edu>]

I have a data set with 131,000 firm observations over 14 years. 
Individual firms may be in the data set between 1 and 14 times. I want 
to keep only those firms that have observations for the entire 14 year 
period.

I've tried all the tricks I know as well as a number of suggestions on 
the stata website, but I haven't had any luck.

thanks for the help,
Mindy Nitkin

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