# Re: st: RE: Heckman self selection bias - selection variable

 From "Mark Schaffer" To statalist@hsphsun2.harvard.edu Subject Re: st: RE: Heckman self selection bias - selection variable Date Thu, 06 Oct 2005 14:12:11 +0100

```Lilach,

I'm not sure if I understand your problem, but you might want to look
at the paper by John Garen (1984), "The Returns to Schooling: A
Selectivity Bias Approach with a Continuous Choice Variable",
Econometrica 52(5).

HTH.

--Mark

Subject:        	st: RE: Heckman self selection bias - selection variable
Date sent:      	Thu, 6 Oct 2005 14:15:00 +0200
From:           	"Maarten Buis" <M.Buis@fsw.vu.nl>
To:             	<statalist@hsphsun2.harvard.edu>

> Dear Lilach
>
> Consider the classic example: you want to explain the wage of women. This is a case where you might expect self-selection, since a considerable proportion of women "choose" not to work. The wage is a continuous variable, but it is only observed when the woman works. The selection equation has one dependent variable, which is dichotomous: is the wage observed (1) or not (0), i.e. does the woman work or not. So the selection equation does not have a continuous dependent variable, but a dichotomous dependent
variable indicating whether the case is selected or not.
>
> Hope this helps,
> Maarten
>
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu]On Behalf Of Lilach_Nachum@baruch.cuny.edu
> Sent: donderdag 6 oktober 2005 4:43
> To: statalist@hsphsun2.harvard.edu
> Subject: st: Heckman self selection bias - selection variable
>
>
>
> I need to conduct Heckman style self-selection bias test.
> For the first stage of this test, the selection probit model, I have a
> number of alternative DVs, all of whom are continuous variables. Can I
> dichotomize a continuous variable, so that it can be used as a DV in the
> probit model?
>
> Will appreciate very much any advice on this.
>
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Prof. Mark E. Schaffer
Director
Centre for Economic Reform and Transformation
Department of Economics
School of Management & Languages
Heriot-Watt University, Edinburgh EH14 4AS  UK
44-131-451-3494 direct
44-131-451-3296 fax