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st: RE: modeling constraint question


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: modeling constraint question
Date   Wed, 27 Apr 2005 11:13:46 +0100

-predict- basically generates predictions given 
the last model fitted. 

Whether you want to apply constraints upstream 
-- to the modelling -- or downstream -- to 
modify predictions for some purpose -- you 
need a separate command, I think. 

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

William P. Kittredge
 
> Does anyone know a way to constrain the predict
> function?  I'm working with a simple funding model
> that the organization is comfortable with:
> 
> funding06 = bx1 + bx2+ bx3+e
> predict funding07
> 
> I'd like to constrain the funding07 values for each
> grantee so that they are +/- a given percent (e.g. if
> the budget goes down 10% each grantee gets 10% less.
> 
> The reason for doing it this way, I'm told, is that
> the variables (e.g. x1) change differently from year
> to year for each grantee and that the 'need' they
> represent is also supposed to alter their funding
> (need based) all else equal.
> 
> I'm pretty new to this, so club me gently if this
> makes no sense.

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