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Re: st: Polynomial in Time in an Unbalanced Panel


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Polynomial in Time in an Unbalanced Panel
Date   Fri, 18 Jun 2010 07:55:39 -0700 (PDT)

--- On Fri, 18/6/10, natasha agarwal wrote:
> I tried
> 
> egen t1=group(year)
> gen t2=t1^2
> gen t3=t1^3
> 
> But am not sure if this is correct for an unbalanced
> panel?

The -egen- step sounds dangerous an un-necessary to me
(regardless of whether this balanced or un-balanced panel
data or cross sectional data). I would just substract 
some meaningfull timepoint from your year variable to 
make sure that 0 zero is located within the range of 
your data. Other than that it looks ok to me.

-- Maarten

--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany

http://www.maartenbuis.nl
--------------------------


      

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