Re: Weights for analysis of HIV+/HIV- urban and rural populations [message #13098 is a reply to message #13083] |
Wed, 20 September 2017 08:09  |
Bridgette-DHS
Messages: 3230 Registered: February 2013
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Senior Member |
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Following is a response from Senior DHS Stata Specialist, Tom Pullum:
I assume you are using Stata with pweights and svyset. The weight can be hiv05 or hiv05/1000000. You will get exactly the same results with either one.
If you want to restrict an analysis to a sub population, then you can do it by including, at the end of the estimation command, something like "if hiv03==0". However, it would be better to construct a variable that is 1 for this subpopulation, e.g. "gen hivneg=1 if hiv03==0" and then put "svy, subpop(hivneg): " in front of (on the same line as) the estimation command. There are good reasons for using the subpop option with svy, even though (in some checks I have done) it produces almost exactly the same results as the "if" command.
Perhaps another alternative would be to include hiv03 as a covariate on the right hand side of the model. If its coefficient is not significant, then you don't need hiv03 in the model. You have to be sure to take account of any values of hiv03 other than 0 and 1. Note that if hiv03 is NA (that is, ".") then hiv05 will be too.
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