# Re: st: Weighted Least Squares

 From Maarten buis To statalist@hsphsun2.harvard.edu Subject Re: st: Weighted Least Squares Date Tue, 15 Apr 2008 15:57:43 +0100 (BST)

```I read your question as follows:
- you have two (or more) variables: x1 = % in zone1, and x2 = % in
zone 2, which must add up to 100%
- x1 and x2 are explanatory variables
- you want these variables to have only one effect instead two (or
more) because you see them as one variable.

Is that correct?

-- Maarten

--- Tam Phan <tamdphan@gmail.com> wrote:

> Hello Stata Users:
>
> I have a quick question on weighted Least squares:  Below is the
> following econometric equation:
>
> Q1+Q2 = alpha + [  (Q1/(Q1+Q2))*X1 + (Q2/(Q1+Q2))*X2 ]b + e
>
> Where X1 and X2 are the same explanatory variables, however with
> different numerical values.  For example, X1 would be the % in one
> zone, and X2 is the percent in another zone.
>
> Is there anything wrong w/ this logic?
>
>
> y1=alpha1+beta1(P)+e
> y2= alpha2 +beta2(P)+v
>
> To obtain the aggregate effect one would sum:
>
> y1+y2=(alpha1+alpha2) +(beta1+beta2)P+(e+v)
>
> Is there anything wrong with the above logic?
>
> Tam
>
> Tam
> *
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>

-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands

Buitenveldertselaan 3 (Metropolitan), room Z434

+31 20 5986715

http://home.fsw.vu.nl/m.buis/
-----------------------------------------

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```