# Re: st: how to create average income of same cohorts?

 From "Austin Nichols" To statalist@hsphsun2.harvard.edu Subject Re: st: how to create average income of same cohorts? Date Wed, 16 May 2007 12:23:06 -0400

```Mirko--
think Scott's code does not work when age is repeated within
region/educ cells, e.g. after an -expand- command on the toy data, and
could tax system memory if age varies widely across cells and there is
a lot of data).

When I read the question, I thought age might not be measured as an
integer, i.e. as floor(elapsed_age), but as a float or double, as I
suspect it usually should be (though common practice dictates
integers), which led me my thinking in another direction, shown below.

This solution is pretty fast and adaptable to a number of related
problems, I suspect, but limited to problems where the "cohort" fuzzy
match variable (age, here) has values that fit in a local (though this
limit could be sidestepped in various ways).  No doubt there is an
even better solution using Mata.

clear
input id   region  educ  age     income
1       2       1       25      5
1       2       1       26      5
2       2       1       29      8
2       2       1       30      8
3       2       1       32      11
3       2       1       33      11
4       1       1       40      5
4       1       1       41      5
5       1       2       37      8
5       1       2       38      8
6       1       2       42      9
6       1       2       43      9
end
g double yref=.
cap prog drop mbyage
program mbyage, byable(recall)
syntax [varlist] [if] [in]
marksample touse
qui levelsof age if `touse', loc(a)
foreach y of local a {
su `varlist' if `touse' & age>=`y'-5 & age<=`y'+5, meanonly
qui replace yref=r(mean) if `touse' & age==`y'
}
end
bys reg educ: mbyage inc
sort id age
li, noo sepby(id)

On 5/15/07, Scott Merryman <smerryman@kc.rr.com> wrote:
```
```An alternative:
egen group = group(region educ)
tsset group age
tsfill, full
tssmooth ma ref= income, w(5 1 5)
keep if id !=.

> -----Original Message-----
> From: Mirko
> William,
> thanks a lot for all the work you have done on this.
```
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```