Stata The Stata listserver
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

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


From   yi jiang <[email protected]>
To   [email protected]
Subject   Re: st: RE: first stage prediction gets negative value for positive observations
Date   Mon, 21 Feb 2005 15:01:03 -0800

thank you Nick. even though i plot the data and the fitted data, the
problem is still there. let me give some examples:
1. X1>0, however, the fitted value of X1 from first stage has negative
observation.
2. 0<X1<1, however, the fitted value of X1 from first stage has
observation bigger than 1.
you name it.
I guess it doesn't matter, but it does look questionable in terms of
how to explaine the meaning of X1.

On Mon, 21 Feb 2005 22:47:39 -0000, Nick Cox <[email protected]> wrote:
> Why not plot the data and your fit,
> if that makes sense?
> 
> Nick
> [email protected]
> 
> 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?
> 
> *
> *   For searches and help try:
> *   http://www.stata.com/support/faqs/res/findit.html
> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/
>
*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



© Copyright 1996–2024 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index