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st: RE: first stage prediction gets negative value for positive observations


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: first stage prediction gets negative value for positive observations
Date   Mon, 21 Feb 2005 22:47:39 -0000

Why not plot the data and your fit,
if that makes sense? 

Nick 
n.j.cox@durham.ac.uk 

yi jiang

> I'm doing a two stage regression. I'm predicting X1 (X1 are all
> positive) at the first stage and then use the predicted value of X1 at
> the second stage.
> However, the predicted value of X1 shows some negative value, which
> makes no sense in terms of data--X1 cannot be negative. any thoughts?

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