Re: st: Sample selection variable for bivariate probit selection

["Carlos Gamero" <gamero@uma.es>]

Dear Maarten,

Thank you very much for your answer. The only question is that I dont think 
I have two selection equations. I think I have one (do you work or not) but 
it must be estimated using a bivariate probit model, because the "being in 
education" decission is not exogenous, i.e., if you do work, then you 
probably find it harder to study (and vice versa). That's why I would like 
to estimate the selection equation as part of a bivariate probit model and, 
then, somehow take account of the selection problem later in the 
satisfaction equation (estimated as another probit model).

Thanks a lot, really.

Carlos Gamero



----- Original Message ----- 
From: "Maarten buis" <maartenbuis@yahoo.co.uk>
To: <statalist@hsphsun2.harvard.edu>
Sent: Friday, January 25, 2008 1:16 PM
Subject: Re: st: Sample selection variable for bivariate probit selection



> --- Carlos Gamero <gamero@uma.es> wrote:
> > In your previous messages you advice me to use heckprob command in
> > order to manage the situation I describe. However, heckprob command
> > is designed to correct sample selection bias when both, main
> > regression (job satisfaction) and selection equation, are probit
> > regressions. But, what happens when you do not have a probit as
> > selection equation but a bivariate probit as it is in my case?
> I read your problem as follows: You are substantively interested in
> work satisfaction (satisfied/not satisfied) and you think you have two
> selection equations: 1) do you work or not, and 2) are you in education
> or not.
>
> If that is the case, than you have just one selection equation: The
> selection is that you cannot be satisfied of dissatisfied with your job
> if you don't have a job. In education or out of education is not a
> selection equation because you can still be satisfied with a job if you
> are in education as long as you also have a job. You are less likely to
> have a job when you are in education, but that just means that being in
> education should be an explanatory variable in your selection equation.
>
> Hope this helps,
> 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 Z434
>
> +31 20 5986715
>
> http://home.fsw.vu.nl/m.buis/
> -----------------------------------------
>
>
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