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st: RE: Identify 1st observation in each group in a panel data model


From   "Scott Merryman" <smerryman@kc.rr.com>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: Identify 1st observation in each group in a panel data model
Date   Mon, 11 Apr 2005 16:22:45 -0500

How about this:

gen DV = 0
bysort code (year): replace DV = 1 if _n == 1


Scott



> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-
> statalist@hsphsun2.harvard.edu] On Behalf Of Dahlia El-Hawary
> Sent: Monday, April 11, 2005 3:59 PM
> To: statalist@hsphsun2.harvard.edu
> Subject: st: Identify 1st observation in each group in a panel data model
> 
> Hi,
> I would very much appreciate your help with the following qusetion.
> 
> I am working with an unbalanced annual panel data of over 50,000
> observations. The data set is made up of firms within countries over a
> time period from 1987 - 2002. I generated a variable called "code" as
> my panel identifier which assigns each firm a number. I also have
> a "countryid" giving each country a number. Year is the variable I am
> using for time.
> 
> I would like to know how to identify the first observation of
> variable "X" for each firm in the panel ?. Specifically I would like
> to generate a dummy variable (DV==1) if the value of the first
> observation for variable X (for each firm) is less than "a", and DV==0
> otherwise.
> 
> Thank you in advance,
> 
> Dahlia El-Hawary
> PhD Candidate
> Economics Department
> George Wshington University
> 
> 
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