# Re: st: weight

 From Steven Samuels To statalist@hsphsun2.harvard.edu Subject Re: st: weight Date Tue, 3 Jul 2007 17:16:57 -0400

```On Jul 3, 2007, at 1:27 PM, Sebastian Kruk wrote:
```
```I have a Stata database and a Excell spreadsheet.
In the first one,  I have a survey microdata of households (v.g.
income, quality of life, poverty, education, employment, housing and
equipment).
In the second one, I have a excell archive with population
projections. I will like to use it to compute a weight for a data in
Stata.
How I form groups by ages and then I use a weight by group of age?
```
What you want to do is called "poststratification."

Suppose the spreadsheet categories and corresponding population projection counts are:

20-29 140,000
30-39 120,000
40-49 300,000
50-59 200,000
60-69 100,000
70-100 50,000

In your Stata data set, create a grouped age variable with the same categories:

egen agegp=cut(age), at(20,30,40,50,60,70)
// Creates a grouped variable & names the categories for the LH endpoints

label define agegp 20 "20-29" 30 "30-39" 40 "40-49" 50 "50-59" 60 "60-69" 70 "70+"
label values agegp agegp

2. Create a variable in Stata to hold the projection counts. You can do this by hand or you can add an "agegp" column to the spreadsheet and use -insheet- to bring them into a stata data set, then -merge- with your data by agegp

By hand:
gen age_ct=140000 if agegp==20
replace age_ct=120000 if agegp==30
replace age_ct=300000 if agegp==40
.
.
replace age_ct=50000 if agegp==70

3. Finally, -svyset- your data. As Friedrich stated, there may already be a "weight" variable. There may also be a stratum variable, and primary sampling unit variable in your microsurvey. These should be documented in the survey codebook.
I assume you have all three, named "final_wt","stratum", "psu".

The -svyset- command is:

"svyset psu [pweight=finalt_wt], strata(stratum) poststrata(agegp) postweight(age_ct)"

4. If you you have separate population counts on age and gender, then you might create a combination age-gender variable and post-stratify on this 12 category variable. Be aware that if you have few people in some categories you may need to combine them.

For example:
gen age_gender = 21 if agegp==20 & gender==1
replace age_gender = 22 if agegp==20 & gender==2
etc.

-Steven

*
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• References:
• st: weight
• From: "Sebastian Kruk" <residuo.solow@gmail.com>