Dear Maarten,
excuse my rather unclear use of terms and definitions. I know that
Seema is working with a to similar dataset for his thesis as I do. So
the dummy hint was rather practical than theoretically founded.
Thanks for pointing that out.
Georg
On 8/31/07, Maarten buis <[email protected]> wrote:
> --- georg wernicke <[email protected]> wrote:
> > The complete references are:
> >
> > Marno Verbeek,
> > A guide to modern econometrics.
> > 2000
> > John Wiley & Sons,
> >
> > and
> >
> > Linders, G. J. M. and H. L. F. de Groot (2006). Estimation of the
> > Gravity Equation in the Presence of Zero Flows.
>
> Thanks
>
> > when using stata for the heckman it will ask you for a selection
> > dependent variable. use the dummy for that.
>
> -heckman- asks you for the selection equation. This may or may not
> contain the dummy you refer to. If you whish to include that dummy, you
> must use the second syntax shown in -help heckman- (otherwise -heckman-
> will fail). This dummy does not need to be specified, but there may be
> situation where it might be practical. However, it has nothing to do
> with Seema's question, as I explained in my previous posts.
>
> 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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