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Re: st: How low can the percentage of uncensored cases be in heckprob?


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: How low can the percentage of uncensored cases be in heckprob?
Date   Tue, 11 Nov 2008 22:00:15 +0000 (GMT)

--- Steven Samuels <sjhsamuels@earthlink.net> wrote:

> I am not familiar with -heckprob-, but I doubt if the *percent* of  
> uncensored observations matters much.
> 
>   -heckprob- fits two probit models. 

There is a bit more going on here, at the second equation you only have
information on those who where selected in the first equation, so
having many people censored means that you loose a lot of information
for the second equation.

-- Maarten

-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands

visiting address:
Buitenveldertselaan 3 (Metropolitan), room N515

+31 20 5986715

http://home.fsw.vu.nl/m.buis/
-----------------------------------------


      
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