Re: st: data management help

[mnitkin <mnitkin@bu.edu>]

Your assumptions about the data are correct.

I tried your suggestion, but "duplicates" is not a valid command on my 
version of Stata. Is there a similar command that might work with pre 
7.0 versions of Stata.
Thanks for the help,
Mindy

Richard Williams wrote:

> At 12:09 AM 10/4/2004 -0400, mnitkin 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.
> >
> > 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.
>
> Something like this might do it.  Lets suppose you want to keep those 
> cases where the same id number occurs 14 times (i.e. there is a first 
> occurrence and then 13 "duplicates").  Lets further assume each firm has 
> a maximum of 1 record per year. Then,
>
> duplicates tag id, gen(nyears)
> keep if nyears == 13
>
>
> -------------------------------------------
> Richard Williams, Notre Dame Dept of Sociology
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