Re: [R] Re : Complex survey analysis help

From: Thomas Lumley <tlumley_at_u.washington.edu>
Date: Sun 01 Oct 2006 - 23:52:17 GMT

On Sun, 1 Oct 2006, justin bem wrote:

> Dear Thomas !
>
> Thank you for you help ! I need and explaination. If I suppress second
> and third stage what become the variance du to second and third stage ?
>
> I have try this
> >E3stage<-svydesign(ids=~stage1id, weight=~wei ...)
> and
> >E3stage<-svydesign(ids=~stage1id+stage2id+stage3id, weight=~weights...)
>
> And I get the same results

Yes, just as in the example on the help page for svydesign.

When the first stage is sampling with replacement the variance estimator is based on the p-expanded cluster totals being a simple random sample from a population distribution.

This is conservative, and better variance estimators are possible in principle. I am hoping to include better estimators in a future version of the package, but I need to do some more reading first -- there does not seem to be agreement on the best variance estimators (except for the impractical one that requires pairwise sampling probabilities). I would welcome suggested references (especially if they are in English).

         -thomas

Thomas Lumley			Assoc. Professor, Biostatistics
tlumley@u.washington.edu	University of Washington, Seattle

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