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Re: declaring child survey in Stata [message #3915 is a reply to message #3914] Thu, 05 March 2015 15:48 Go to previous messageGo to previous message
Trevor-DHS is currently offline  Trevor-DHS
Messages: 789
Registered: January 2013
Senior Member
1a) Why are you pooling the data? What benefit do you get from pooling the data over running two separate analyses? Are you trying to compare changes over time?
1b) You cannot use the PSU and stratum variables as they are. You need to create new PSU and stratum variables that are specific to each survey, e.g. egen newpsu = group(survey_year v001) and egen newstrata = group(survey_year v023)
1c) You probably have to denormalize the weights for your analysis. There are several posts on the forum about denormalization.
1d) your svyset command should look more like svyset newpsu [pweight=wgt], stratum(newstrata) where wgt is the denormalized weight. Even if you weren't denormalizing, you would need to first divide v005 by 1000000, but as you are pooling data you should be denormalizing the weights.

2) If you don't use svyset and svy: regress (or similar commands) then your tests of significance will be incorrect.

3) For the weight, see how it is used above in the svyset command. Whenever you use an svy: command Stata will refer to the weight in the svyset command.

4) Using the weight when not using the svy commands:
gen wgt=v005/1000000
tab var1 var2 [iw=wgt]

Using the weight with the svy commands:
gen wgt=v005/1000000
svyset v001 [pweight=wgt], stratum(v023)
svy: tab var1 var2

[this assumes the strata are in v023 - sometimes they are in v022 and sometimes they need to be created. See other posts concerning the strata variables to use.]

5) The variables you mention are standard variables, but I would never copy and paste data as you suggest. You should use the commands for combining datasets: http://www.stata.com/manuals13/u22.pdf
 
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