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Re: st: Svy commands for analysis of two populations with differentsurvey designs

From   vinkwai wong <>
To   "" <>
Subject   Re: st: Svy commands for analysis of two populations with differentsurvey designs
Date   Mon, 26 Jan 2004 09:15:43 +0800

Hillgrove, Tessa (SA)!

     though i am not quite sure if my thinking is right,but i am willing to share my thinking here,and hop it can be helpful.
     i think it is a bad idea to combine the tow datasets into one.mybe you should analysis the tow dataset separately.and then compare the resulte you get.(ie,from dataset1,maybe you can inferen the state of the population1......then you can compare the states of 2 pop after you get the estimation of each population.)


======= 2004-03-26 07:35:30 您在来信中写道:=======

>I have a question relating to the svy commands in Stata. Is there a way to
>perform analysis between two populations while taking into account the
>different survey design used select the samples; or do I need to ignore my
>survey design when performing analysis between the populations? 
>The survey questionnaire for both groups was identical. My problem is that
>my two different populations have different survey sampling designs.
>Population 1 sample was a proportionally stratified random sample, selected
>from the electoral roll to reflect the current estimates of the age and sex
>distribution in the population, with a total of 12 strata. Population 2
>sample was random sample from the entire lists of registered physicians in
>specified categories (eg GPs, surgeons), with a total of 6 strata. 
>The problem is that I want to perform analysis comparing variables in both
>populations, and I'm not sure how to do this while taking into account
>different survey designs used between the two populations (ie using the
>sample weightings). The weightings and the finite population correction
>variable and have been calculated for the two samples independently, but the
>data from the two populations have been combined into one dataset for
>analysis between populations (each strata group has a unique number).
>However, some unexpected numbers have made me think that I am not
>calculating these correctly. For example, when using the command svytab, the
>"Population size" is equal to the combined total of the two populations,
>even though they are not really independent (as the Population 2 is also
>part of the Population 1). This makes me suspect that calculations using the
>svy commands are assuming the same survey design was used for the whole
>dataset, when there were two different designs used.
>I would appreciate any suggestions about how I can get around this
>Tessa Hillgrove
>Project Officer
>Quality and Business Systems
>Australian Red Cross Blood Service (SA)
>301 Pirie Street Adelaide South Australia 5000
>Phone: (08) 8422 1364
>Fax: (08) 8422 1300 
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               vinkwai wong

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