Home » Data » Weighting data » PSU and strata identifiers - Egypt
| PSU and strata identifiers - Egypt [message #10199] |
Thu, 07 July 2016 13:28  |
Nora
Messages: 14
Registered: May 2016
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I am trying to use the svyset option to weight my data. I am using pooled data for Egypt for years 1995,2005 and 2014 and restricting my sample to women who participated in the domestic violence module.
1.I am not sure what variable to specify in the PSU and strata. As v021 is labelled PSU and v022 is labelled as sample strata for the three surveys, would this syntax be correct?
svyset [pw= domestic violence wgt], psu(v021) strata(v022)
What does this result mean:
pweight: wt_dv
VCE: linearized
Single unit: missing
Strata 1: v022
SU 1: v021
FPC 1: <zero>
2.Also, is it okay to run this code with pooled data from three surveys?
Thank you.
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| Re: PSU and strata identifiers - Egypt [message #10203 is a reply to message #10199] |
Fri, 08 July 2016 07:57  |
Bridgette-DHS
Messages: 3215
Registered: February 2013
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Senior Member |
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Following is a response from Senior DHS Specialists, Tom Pullum and Trevor Croft:
To be clear, the files are EGIR33 (the 1995 survey), EGIR51 (the 2005 survey), and EGIR61 (the 2014 survey).
In most DHS surveys, PSUs and clusters are the same, so either v021 or v001 can be used as the cluster id. However, for most surveys of Egypt, including the three you are using, there are two clusters per PSU. You should use v021 as the PSU id, as you are doing, but with the following modification for the first survey. For that survey, v021 is incorrect and should be reconstructed with "v021 = int(v001/10000)". After that change, you can use v021 as the id for PSU in all three surveys.
In all three surveys the sample strata are urban and rural areas within each governorate. That must be constructed in the first two surveys. For example, in those two surveys you could use these two lines: "rename v023 v023_original" and "egen v023 = group(v023_original v025)". For the third survey, just use v023 as it is.
We would never recommend that you replace the original file with revised variables. If you make changes using original variable names, as just suggested, you should save with another file name or you should just put those changes in a program and not save the data file.
Yes, you can pool the surveys into a single file. You can include a variable "survey" or you can distinguish them with v000. In the three surveys, v000 is coded EG3, EG4, and EG6, respectively. You could reduce the files to just the variables you need before appending them.
You could get unique identifiers in the pooled file, after you have reconstructed v021 and v023 as described above, with "egen cluster=group(v000 v021)" and "egen stratum=group(v000 v023)" and then "svyset cluster [pweight=wt_dv], strata(stratum) singleunit(centered)" . There have been many postings on possible rescaling of the weights when surveys are pooled. In this case I would leave the weights alone, because I assume (and hope) you are really just looking at changes between surveys rather than, say calculating means or percentages that combine all three surveys.
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| Re: PSU and strata identifiers - Egypt [message #15993 is a reply to message #15909] |
Wed, 17 October 2018 10:25 |
Bridgette-DHS
Messages: 3215
Registered: February 2013
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Senior Member |
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Following is a response from Senior Sampling Specialist, Mahmoud Elkasabi:
In general, you need to check the sampling design appendix to figure out the stratification variables and then construct it in a proper way.
Regarding the 1988 EDHS survey, see page 174 in the final report: "All list of PSUs allocated according to governorate and residential sector (urban/rural)" This means that similar to the other surveys, governorates by urban/rural were used as design strata for the 1988 EDHS.
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