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Re: st: weight in a field survey


From   "Michael I. Lichter" <mlichter@buffalo.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: weight in a field survey
Date   Mon, 22 Mar 2010 17:43:23 -0400

Estelle,

If this is a true PPS design, you shouldn't have to weight for anything except for unequal probabilities of selection across strata. (Unequal probabilities for village selection are balanced out by unequal probabilities for household selection.) That weight would be, as I think you're saying, weight for stratum i = 1/(proportion of total population in stratum i). Of course, you will also want to add a weight for household size when doing individual-level tabulations.

Michael

Estelle PASQUIER wrote:
Dear statlist,
We are conducting a field survey on
malaria. Our population is sampled by stratifying it in rural and urban
settings (first step) then selecting villages with a probability proportional
to their population sizes. The last step consists in selecting randomly a fixed
number of households in the village. I am a little bit concern with the sample
weights I have to choose with svy: my suggestion would be to calculate the
stratum weight as the ratio of total population on population in each stratum;
to calculate the cluster weight as the inverse of the sampling probability, and
then to use the product of these two weights as final weight. Am I right? My second concern is to know if I there is anything to do for the last step of this sampling design? Thanks for any help, Estelle


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Michael I. Lichter, Ph.D. <mlichter@buffalo.edu>
Research Assistant Professor & NRSA Fellow
UB Department of Family Medicine / Primary Care Research Institute
UB Clinical Center, 462 Grider Street, Buffalo, NY 14215
Office: CC 126 / Phone: 716-898-4751 / FAX: 716-898-3536

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