Re: st: Sequential Probit

[elin.vimefall@oru.se]

Thanks a lot!
I still have one question. I want to take into accont that there is some unobserved heterogenity term for the individual, which is constant across the different schooling decisions. 
Can I do that in this setting?

//Elin

----- Original Message -----
From: Maarten buis <maartenbuis@yahoo.co.uk>
Date: Thursday, March 3, 2011 10:21
Subject: Re: st: Sequential Probit

> --- On Thu, 3/3/11, Elin Vimefall wrote:
> > I would like to use a sequential probit with three steps to
> > analyze schooling of children:
> > 
> > Step 1: Do the child have  any formal education
> > Step 2: Have the child finished primary education
> > Step 3: Is the child currently in secondary education (or
> > above)?
> > 
> > Does anyone know how to do this in stata?
> 
> Say you have an education variable, ed, where ed==1 when child 
> has no formal education, ed==2 when child has finish primary
> and stopped, and ed==3 when child is currenltly in secondary
> education. Then you create two new variables:
> 
> gen byte ed12 = ed >= 2 if !missing(ed)
> gen byte ed23 = ed == 3 if !missing(ed) & ed12 == 1
> 
> So ed12 is 1 when the child passed the first transition and 0
> when it failed, and ed23 is 1 when the child passed the 
> second transition, 0 when it failed and missing when it was
> no longer "at risk", that is, the child failed the first 
> transition.
> 
> Say you wanted to include the variables x1 and x2 as your
> explanatory variable, then you would estimate a sequental
> probit as follows:
> 
> probit ed12 x1 x2
> probit ed23 x1 x2
> 
> [Warning: shameless self-promotion coming up]
> 
> Personally I prefer the sequential logit, as I find the
> results easier to interpret, there is a nice decomposition
> possible the relates the effects of x1 and x2 on the highest
> achieved outcome to the effects of these variables during
> each transition (I should think it is nice as I developed
> it...), and I developed some tools to investigate the 
> potential influence of unobserved variables in this model.
> 
> The decomposition is discussed here:
> <http://www.maartenbuis.nl/dissertation/chap_6.pdf>
> 
> The tools for investigating the potential influence of 
> unobserved heterogeneity are discussed here:
> <http://www.maartenbuis.nl/publications/uh.html>
> 
> Both are implemented in the -seqlogit- package, which can 
> be downloaded by typing in Stata -ssc install seqlogit-
> 
> > Is there any different between a sequential probit model
> > and a multivariat probit with sample selection?
> 
> Yes, the latter model estimates more structure on the error 
> terms. The problem with that is that there is obviously 
> very little information in your data on that structure, so
> model assumptions tend to be too important in such models 
> for my taste, but tastes notoriously differ.
> 
> Hope this helps,
> Maarten
> 
> --------------------------
> Maarten L. Buis
> Institut fuer Soziologie
> Universitaet Tuebingen
> Wilhelmstrasse 36
> 72074 Tuebingen
> Germany
> 
> http://www.maartenbuis.nl
> --------------------------
> 
> 
>      
> 
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