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Weighting data [message #2992] 
Tue, 30 September 2014 06:57 
pjoshi
Messages: 6 Registered: September 2014

Member 


Hi,
I am working with the 2011 data set for Nepal and I had a question regarding the sample weights. I have been performing very basic calculations to try and replicate the results of DHS 2011 report to understand the data. However, my numbers don't match the numbers on the report and I want to check if I am missing something important. In order to apply the sample weights when performing calculations on STATA, is the following process correct?
Example: to calculate the mean number of household members
gen weight= HV005/1000000
svyset HV021 [pweight=weight], strata( HV023)
I get the following message after this:
pweight: weight
VCE: linearized
Single unit: missing
Strata 1: HV023
SU 1: HV021
FPC 1: <zero>
Next, I entered
svy: mean V009
I get a mean of 4.6 while the number of the DHS report is 4.4. I would really appreciate any help on this.
Thanks!




Re: Weighting data [message #3028 is a reply to message #3013] 
Mon, 06 October 2014 10:23 
BridgetteDHS
Messages: 2742 Registered: February 2013

Senior Member 


Here is additional comments from Senior Specialist, Tom Pullum:
If all you want to do is to calculate mean household size, then you do not need to make an adjustment for clusters and strata. That adjustment only affects the estimates of standard errors. You just need the adjustment for weights. You can use this with the HR file (NPHR60FL.dta):
summarize hv009 [iweight=hv005/1000000]
Or you can do the following (for pweights, it is not necessary to divide by 1000000):
svyset [pweight=hv005]
svy: mean hv009
Both of those will give 4.6289, which is probably what you were getting and does not match with the value in the report, 4.4. The reason you are not getting 4.4 is that the DHS figure is limited to de facto members of households, i.e. respondents for whom hv103=1 rather than 0. Try the following, with the PR file rather than the HR file, i.e. with NPPR60FL.dta:
collapse (sum) hv103 (first) hv005, by(hhid)
summarize hv103 [iweight=hv005/1000000]
This will give a mean of 4.39408, which matches the report.



Re: Weighting data [message #3032 is a reply to message #2992] 
Mon, 06 October 2014 11:47 
TrevorDHS
Messages: 776 Registered: January 2013

Senior Member 


Just a further clarification in case the two responses are confusing. Tom's response is a way of getting the mean number of de facto household members. To get the number of de jure household members (as used in the table in the report) you would use hv102 (usual member) instead of hv103 (slept in the household the previous night) in Tom's response.
Similarly, you can just use the HR file and get the mean of hv012 for mean number of de jure household members, or use hv013 for the mean number of de facto household members.
Mean number of de jure household members: 4.44513
Mean number of de facto household members: 4.39408
Table 2.10 in the survey report provides the mean number of de jure household members.



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