st: Re: Full-time workers only regression

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

Peter,

The two options that you mentioned are quite different.

If you run "y" on the full data including a dummy for full-time labourers, 
then you would be assuming that the only difference between full-time 
labourers and others is given by the dummy. The parameters for all other 
variables included in the model are restricted to be the same across labour 
market categories. For example, if one of your regressors is the years of 
schooling, then the estimated parameter \beta_{schooling} would tell you 
that the returns to schooling are the same regardless of the labourer being 
a part or full-time worker.

You second option (restrict estimation to full-time workers) implies that 
the model is only valid for full-time workers. You wouldn't be able to say 
anything about part-time workers.

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 ----- 
From: "peter harper" <pharper11@yahoo.co.uk>
To: <statalist@hsphsun2.harvard.edu>
Sent: Wednesday, May 31, 2006 7:33 PM
Subject: st: Full-time workers only regression



> Dear Statalist
>
> This is a simple question. I am using a cross-section data with different 
> firms and workers. I want to run a regression on full-time workers only. 
> Would it be best to put the variable, say, flprt in the regression which 
> indicates whether the worker works full or part-time and using the dummy 
> variable for full-time, frlprt2; where frlprt2=full-time workers.
>
> (2) Or run
>
> y  x1 x2 x3 if flprt==2
>
> where frlprt2=full-time workers.
>
> Thanks
>
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