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st: RE: Panel Data Programing issues with apologies


From   n j cox <n.j.cox@durham.ac.uk>
To   statalist@hsphsun2.harvard.edu
Subject   st: RE: Panel Data Programing issues with apologies
Date   Thu, 24 Apr 2008 13:39:22 +0100

The FAQ

<http://www.stata.com/support/faqs/data/members.html>

has a section on "7. Mapping from arbitrary identifiers to integers 1 and above" which may help here.

Nick
n.j.cox@durham.ac.uk

philippe van kerm replied to Jeremy Page

<SNIP>

> I am working with a panel data set which has identifiers by
> household
> (hhid) and individual (id). I am trying to get information about
> the
> mothers education, which is located in the parents row, into
> children's row. I figured out how to do this as long as there is
> only one mother in each household. The problem is there are some
> households with more than one mother per household. "momid"
> indicates
> which id is the mother in the household and is a number between 3
> and
> 19
>
> hhid id edu momid (Want mom edu)
> 1 1 4 0 .
> 1 2 0 0 .
> 1 3 6 5 3
> 1 4 8 5 3
> 1 5 3 0 .
> 1 6 2 3 6
> 1 7 4 3 6

In this particular example, where 'id' is consecutively numbered 1,2,3.. within each household, there is an easy solution:

bys hhid (id): gen momedu = edu[momid] if momid>0

This works whenever 'id' is equal to _n (within each 'hhid') after you sort on hhid id.


Now, in a more general case, where 'id' may not be related to '_n', I believe that it is easier to "merge the dataset on itself":

preserve
// generate a file of 'mothers'
tempfile a
keep hhid id edu
rename id momid
rename edu momedu
sort hhid momid
save `a' , replace
restore
// then merge the mothers to the children
sort hhid momid
merge hhid momid using `a' , nokeep uniqusing
sort hhid id
drop _merge

I would be curious to see a way to do it with explicit subscripting, however.

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