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Re: st: data management help

From   mnitkin <[email protected]>
To   [email protected]
Subject   Re: st: data management help
Date   Mon, 04 Oct 2004 00:43:08 -0400

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,

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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