[R] weighted mean

[Markus Jäntti]

On Wed, 2003-11-26 at 01:28, MZodet at ahrq.gov wrote:
> How do I go about generating a WEIGHTED mean (and standard error) of a
> variable (e.g., expenditures) for each level of a categorical variable
> (e.g., geographic region)?  I'm looking for something comparable to PROC
> MEANS in SAS with both a class and weight statement.
> 

I asked this question a few years ago and this is the anwer I got works:

see 
http://www.r-project.org/nocvs/mail/r-help/1999/2160.html

tapply(seq(along=wage), list(Educc,Year), 
       function(i, x=wage, w=weight)  weighted.mean(x[i], w[i]))

(wage and weight are the variable of interest and weight, while Educc
and Year are the factors)

Regards,

Markus
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> Marc
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-- 
Markus Jäntti <markus.jantti at iki.fi>
Abo Akademi University