# Re: st: Re: Question re Heckman

 From Adam Przeworski To statalist@hsphsun2.harvard.edu Subject Re: st: Re: Question re Heckman Date Sat, 08 Jul 2006 06:04:30 -0400

```Much appreciated,

Carroll and Milton Petrie Professor
Department of Politics
New York University
New York, NY 10003

----- Original Message -----
From: "R.E. De Hoyos" <redeho@hotmail.com>
Date: Friday, July 7, 2006 6:47 pm
Subject: st: Re: Question re Heckman

>
> Yes they do. To eliminate them, you can either create a vector of
> coefficients without the Mills' parameter:
>
> After heckman, type
> mat B = e(b)
> scalar df = (e(df_m)+)
> mat coef = b(1,1..df)
> mat score nomills = coef
>
>
> Alternatively you can compute the Mills with option -mills-,
> predict xb, use
> the parameter of the Mills' ratio to multiply it by the value of
> the Mills
> and finally subtract it from the xb prediction.
>
> I hope this helps,
> Rafa
> ________________________
> Rafael E. De Hoyos
> Faculty of Economics
> University of Cambridge
> CB3 9DE, UK
> www.econ.cam.ac.uk/phd/red29/
>
>
>
>
>
> ----- Original Message -----
> To: <statalist@hsphsun2.harvard.edu>
> Sent: Friday, July 07, 2006 10:10 AM
> Subject: st: Question re Heckman
>
>
> > Does anyone know whether HECKMAN predict, xb included the values
> of the
> > Mill ratio in the predicted values? If yes, how to eliminate it?
> >
> > Carroll and Milton Petrie Professor
> > Department of Politics
> > New York University
> > 726 Broadway, Room 722
> > New York, NY 10003
> > *
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> >
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```