Statalist


[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

Re: st: Weighted Least Squares


From   "Tam Phan" <tamdphan@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Weighted Least Squares
Date   Tue, 15 Apr 2008 12:23:50 -0400

Maarten, X1 = % and X2= %, however, X1 +X2 does not necessary have to
add up to 100% (as a matter of fact they dont).

The % are calculated based on the zone, they are not calcualted across
zone (say zone 1 and zone 2).

Basically the explanatory variables are at a zone level, however, the
regression is taking place at a higher level.  In order to "adjust"
the zone explanatory varaibles, these are weighted to the higher
level.

Tam

On 4/15/08, Maarten buis <maartenbuis@yahoo.co.uk> wrote:
> 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?
> >
> > How about this econometric model:
> >
> > 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
> > *
> > *   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/
> >
>
>
> -----------------------------------------
> Maarten L. Buis
> Department of Social Research Methodology
> Vrije Universiteit Amsterdam
> Boelelaan 1081
> 1081 HV Amsterdam
> The Netherlands
>
> visiting address:
> Buitenveldertselaan 3 (Metropolitan), room Z434
>
> +31 20 5986715
>
> http://home.fsw.vu.nl/m.buis/
> -----------------------------------------
>
>
>      ___________________________________________________________
> Yahoo! For Good helps you make a difference
>
> http://uk.promotions.yahoo.com/forgood/
> *
> *   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 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index