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RE: st: Creating weights


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: Creating weights
Date   Thu, 10 Nov 2005 11:52:42 -0000

This solves Ilaria's problem, but by restructuring 
the data. With the assumed variables -zip- and -pop- 
you can:

egen tag = tag(zip) 
su pop if tag, meanonly 
di "Total is " r(sum) 
gen wgt = pop / r(sum) 

The trick here is that -egen, tag()- selects 
precisely one instance of each -zip-, as 
the problem requires. It has that one narrow
rationale for existence. 

There are also ways of doing this with -by:-, 
but I doubt that any is easier to follow. 

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

Svend Juul
 
> Ilaria wrote:
> I have the population per zipcode of all postcodes of a 
> country. I wanna
> create a weight, which results from the population per zipcode divided
> by total population.
> 
> My questions:
> 1. The population per zipcode is repeated many times in the file. To
> make the weight I only need to count it once. How can I do so?
> 2. I don't have the value for the total population. How can I have it?
> --------------------------------------------------------------
> 
> If yout have the two variables -zip- and -pop- you can:
> 
>     sort zip
>     drop if zip==zip[_n-1]
>     egen totpop=total(pop)
>     gen wgt=pop/totpop
> 
> Hope this helps
> Svend
> __________________________________________
> 
> Svend Juul
> Institut for Folkesundhed, Afdeling for Epidemiologi
> (Institute of Public Health, Department of Epidemiology)
> Vennelyst Boulevard 6
> DK-8000  Aarhus C, Denmark
> Phone: +45 8942 6090
> Home:  +45 8693 7796
> Email: sj@soci.au.dk
> __________________________________________
> 
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