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st: Re: data management help


From   Christopher F Baum <baum@bc.edu>
To   statalist@hsphsun2.harvard.edu
Subject   st: Re: data management help
Date   Mon, 4 Oct 2004 07:21:49 -0400

On Oct 4, 2004, at 2:33, Mindy wrote:

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.

piece of cake:

bysort firm: keep if _N==14

A harder problem is to impose a condition like 'companies must have at least four consecutive years of earnings data.' I have dealt with that successfully (with a little help from Nick and -tsspell-).

Kit Baum, Boston College Economics baum@bc.edu
http://ideas.repec.org/e/pba1.html

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