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Calculating malaria prevalence (Tanzania: Standard AIS, 2011-12) Mon, 21 November 2016 06:19
 NinaB Messages: 1Registered: November 2016 Location: Basel, Switzerland Member
Hi,

I'm trying to reproduce the malaria prevalences (by mRDT and microscopy) for children 6-59 months which can be found in the Tanzania AIS 11/12 final report on page 157. I watched the DHS youtube videos on sampling and weighting and read some other threads in this forum. However, I was not able to get exactly the same numbers as in the report. I'm using the household member dataset (PR) and my stata code so far looks like this:

```*Parasitemia (via microscopy) in children 6-59 months
gen micmalpos=0
replace micmalpos=(hml32==1)
lab var micmalpos "Parasitemia (via microscopy) in children 6-59 months"

*Parasitemia (via mRDT) in children 6-59 months
gen rdtmalpos=0
replace rdtmalpos=(hml35==1)
lab var rdtmalpos "Parasitemia (via mRDT) in children 6-59 months"

*Creating weight variable
gen wgt=hv005/1000000

*Survey setting the data
svyset [pw=wgt], psu(hv021) strata(hv023)

*Proportion of children 6-59 months old with malaria infection (microscopy) by Region
svy: mean micmalpos if hc1>=6 & hc1<=59 & hml33==0, over(hv024)

*Proportion of children 6-59 months old with malaria infection (mRDT) by Region
svy: mean rdtmalpos if hc1>=6 & hc1<=59 & hml33==0, over(hv024)```

Does anyone have an idea what I'm doing wrong. Thanks for helping me.
Nina
Re: Calculating malaria prevalence (Tanzania: Standard AIS, 2011-12) [message #11255 is a reply to message #11236] Wed, 23 November 2016 16:11
 Liz-DHS Messages: 1264Registered: February 2013 Senior Member
A response from malaria expert, Dr. Lia Florey,
Hi Nina,

It looks as though you are using the correct approach. When examining this particular dataset I see that a crosstab of hml33 and hml32 produces some unusual results. Same with the crosstab of hml33 and hml35. In order to replicate the estimates from the final report I would recommend the following changes to your code:
```*Proportion of children 6-59 months old with malaria infection (microscopy) by Region
svy: mean micmalpos if hc1>=6 & hc1<=59 & hv103==1 & (hml32==0|hml32==1), over(hv024)

*Proportion of children 6-59 months old with malaria infection (mRDT) by Region
svy: mean rdtmalpos if hc1>=6 & hc1<=59 & hv103==1 & (hml35==0|hml35==1), over(hv024)

The hv103 specifies that children who slept in the household the night before the survey (de facto).
You might also try running tabulations instead of means:
svy: tab hv024 micmalpos if hc1>=6 & hc1<=59 & hv103==1 & (hml32==0|hml32==1), row ci per
svy: tab hv024 rdtmalpos if hc1>=6 & hc1<=59 & hv103==1 & (hml35==0|hml35==1), row ci per
```

I hope that this solves your problem.

Best,
Lia
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