st: Re: HecKman two step procedure and prediction

["R.E. De Hoyos" <redeho@hotmail.com>]

Alfredo,

The option -stdp- after -predict- in Heckman's estimation, produces the 
standard error of the fitted value. Where the fitted value derives from the 
"population" un biased parameters estimates, i.e. taking into account 
selectivity [y^hat = {xb^hat | Pr(y = observed | z)}].

I hope I got your question right,

Rafa
________________________
R.E. De Hoyos
Faculty of Economics
University of Cambridge
CB3 9DE, UK
www.econ.cam.ac.uk/phd/red29/

----- Original Message ----- 
From: "Alfredo Ariza Alfaro" <aarialf@upo.es>
To: <statalist@hsphsun2.harvard.edu>
Sent: Wednesday, June 22, 2005 7:47 PM
Subject: st: HecKman two step procedure and prediction



> Hi everyone!
>                      I want to predict  wages for women who do not work,
> so I am using the Heckman two step procedure to calculate wages for
> participants accounting for selection. To predict wages for non
> participants accurately I want to use the standard error of the
> prediction instead of using just the mean. Using "predict  var , stdp"
> predicts the standard error of the prediction taking into account the
> Mills ratio? Or is just calculating the standard error of the linear
> regression without taking into account the selection?
>
> Thank you very much.
>
> Regards.
>
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