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Re: st: weigths


From   "Anthony Gichangi" <anthony@stat.sdu.dk>
To   <statalist@hsphsun2.harvard.edu>
Subject   Re: st: weigths
Date   Sun, 1 Aug 2004 11:50:01 +0200

hi Antonio
The square root will automatically be taken when you specify
regress y x1 x2 x3 [aweight=pop]  see Techinical note on 
Weighted regression page 343 N-R manual. So if you specify
gen wt=sqrt(pop)
regress y x1 x2 x3 [aweight=wt]
you will be doing this twice. I guess you don't want to do that..

Regards
Anthony

----- Original Message ----- 
From: "Antonio Rodrigues Andres" <ara@sam.sdu.dk>
To: <statalist@hsphsun2.harvard.edu>
Sent: Tuesday, August 03, 2004 11:04 AM
Subject: Re: st: weigths


> i think that it is correct to use
> 
> gen wt=sqrt(pop)
> regress y x1 x2 x3 [aweigth=wt]
> 
> 
> >>> ara@sam.sdu.dk 08/03/04 10:41AM >>>
> My
>  dependent variable is the mortality rate. Since the variance of
> ln(d/p)
>  is inversely proportional to p (population), this implies 
> heteroskedasticity. To correct for it, observations should be weighted
> 
> by the square root of the denominator of the mortality rate, i.e.,
>  population. In Stata,   i am using
>  
>  xi: regress y x1 x2 i.country i.year [w=1/pop], 
>  Is that correct? I might also use the robust option
>  I would appreciate any answers
> > Antonio
> 
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