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Re: st: svyset for a multistage sampling design


From   "Michael I. Lichter" <MLichter@Buffalo.EDU>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: svyset for a multistage sampling design
Date   Thu, 20 Aug 2009 19:31:41 -0400

Tomeka,

1. If you don't supply a finite population correction option for the first stage [svyset psu, fpc()], svyset will ignore your second stage. 2. What are your school strata and how many of the strata have only only psu in them -- and why? It doesn't look to me like school is a stratifying variable -- it's your second stage sampling unit which will be ignored without the FPC.

-ml

Tomeka Davis wrote:
I am trying to use the set of svy commands to analyze data collected using a multi-stage design.  The first stage of sampling involved counties that were selected proportional to their size (N~100).  Next, schools were sampled (N~400), and then students were randomly sampled within schools.
In this context, the county is the psu and the school is the strata. I am not sure how strata with one sampling unit were treated. Because I must have this option in STATA, I choose the certainty option since it contributes nothing to the standard error. Without the option, the program does not calculate standard errors. My syntax looks like : svyset county [pweight=studentweight], strata (school) ||_n, singleunit (certainty) The problem is that I am not clear if STATA is using all of the stages. After I enter the command, I get a message that says: "Note: stage 1 is sampled with replacement; all further stages will be ignored". I would appreciate any comments.


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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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