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Re: st: QUERY: svyset for a single stage survey with strata and clusters


From   Steven Joel Hirsch Samuels <sjhsamuels@earthlink.net>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: QUERY: svyset for a single stage survey with strata and clusters
Date   Tue, 21 Aug 2007 18:26:26 -0400

David, your specification is incorrect, but your question cannot be answered without one piece of information: was sampling with or without replacement? I'll assume that it was without replacement, the most likely method. In that case, do the following:

1. Create a variable nschools, which is the number of schools in each stratum--the population number not the sample number.

Code Follows:

/ ************************************************************************ **********/
gen finalwt=1/include
gen fpc2=1
svyset [pweight=final_wt] school, strata(schtype) fpc(nschools) || _n, fpc(fpc2)

/ ************************************************************************ **********/

If your purpose is to do statistical tests or other analytic comparisons, do NOT include the "fpc" (finite population correction) terms (WE Deming, Some Theory of Sampling, Wiley, 1950 (Dover, 1984)). The fpc terms are appropriate only for descriptive studies.


-Steven



On Aug 21, 2007, at 11:40 AM, DavidB.epid@public-health.ucl.ac.uk wrote:


Dear Statalist,
I have a survey design which runs as follows:

12 types of schools in London were identified. The type of school is
in a variable called 'schtype'. We sampled at random a certain
number of schools of each type. The school identifier is called 'schl'.
The selection school probability is held in a variable called 'include'.
In each school all children were sampled regardless of the number of
children.

Hence I take it the strata variable is 'schtype', the cluster variable is
'schl' and the fpc is 'include'.

Am I correct to write the svyset command as:

svyset schl, strata(schtype) fpc(include) vce(linearized)

Thank you for any help you can offer.

David Boniface.

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Steven Joel Hirsch Samuels

sjhsamuels@earthlink.net
18 Cantine's Island
Saugerties, NY 12477
Phone: 845-246-0774
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