st: Re: data management help

[Christopher F Baum <baum@bc.edu>]

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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