st: Re: correction variance- cov matrix panel data sample selection

["Rodrigo A. Alfaro" <raalfaroa@gmail.com>]

Did you try -heckman-?? 
----- Original Message ----- 
From: <ncdcta00@uniroma2.it>
To: <statalist@hsphsun2.harvard.edu>
Sent: Sunday, May 13, 2007 2:06 PM
Subject: st: correction variance- cov matrix panel data sample selection



> Dear statalist, Do you know some routine or reference for correction  
> the standard error and variance matrix in panel data sample selection?
> I calculate the inverse Mills' ratio every year, and after I put this  
> in a simple regression for correctin the selection, but standard error  
> and coefficientes are bias, so I need to corecct them.
>
> Thanks for your help.
> Best,
> Catia
>
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