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Re: st: prediction


From   Raymond <statasas@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: prediction
Date   Fri, 5 Aug 2005 12:25:27 -0400

Can you give me more details about the programming?

The command I'm using are:
xi: poisson death i.age i.period i.gender, exposure (population)
After the regression , I want to estimated death from the effect of
age and period, while setting the effects of gender to zero.

Thanks!



On 8/5/05, Richard Williams <Richard.A.Williams.5@nd.edu> wrote:
> At 11:56 AM 8/5/2005 -0400, Raymond wrote:
> >if I run a regression without the dummies, then the coefficients of
> >the rest variables will be different.
> >What I need to do is using the coefficient of the independent
> >variables calculated while gender is included to estimated the
> >dependent variable while gender is exluded from the prediction
> >equation.
> 
> First off, you probably don't want to do that.  You would be using
> parameter estimates that no model has actually generated.  I very strongly
> suspect that what you propose doing is the wrong way to go but then you
> know your work better than I do.  (Students occasionally want to compute
> predicted values based on some hypothetical set of values, and they ask me
> whether the non-significant coefficients should just be treated as zero; I
> say no, either leave them as is or re-estimate the model with those
> variables dropped.)
> 
> But, if you are bound and determined to do it anyway, see this recent
> message from Vince Wiggins:
> 
> http://www.stata.com/statalist/archive/2005-07/msg00617.html
> 
> You could just modify the foo.ado program he shows to set the coefficients
> to 0.
> 
> Yet another possibility would be to do a -gen- command yourself, leaving
> out the dummy vars; or do a -predict- command followed by a -replace- where
> you subtract the contribution created by the dummies.
> 
> 
> -------------------------------------------
> Richard Williams, Notre Dame Dept of Sociology
> OFFICE: (574)631-6668, (574)631-6463
> FAX:    (574)288-4373
> HOME:   (574)289-5227
> EMAIL:  Richard.A.Williams.5@ND.Edu
> WWW (personal):    http://www.nd.edu/~rwilliam
> WWW (department):    http://www.nd.edu/~soc
> 
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