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Re: st: Creating values for ID variables


From   "Austin Nichols" <austinnichols@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Creating values for ID variables
Date   Thu, 16 Aug 2007 09:35:26 -0400

Prabal Kr. De--
There is a trick using explicit subscripting, which requires you have
no gap in individual IDs and that they correspond to observation
numbers within household, as they do in your example. Then you can
just:

bys hhid (iid): g fathered=grade[fatherid]
bys hhid (iid): g mothered=grade[motherid]

If you have gaps in individual IDs, you have to use some trickery
involving -fillin- to exploit the same trick.  Here is an example that
tests for gaps and automates the trickery:

clear
input hhid  iid fatherid motherid grade
      1001    1     .         .    6
      1001    2     .         .    5
      1001    3     1         2    3
      1001    4     1         2    3
      1002    1     .         .    5
      1002    2     .         .    6
      1002    3     1         2    8
      1002    4     .         .    8
      1002    5     3         4    1
      1002    7     3         4    1
end
cap bys hhid (iid): assert iid==iid[_n-1]+1 if _n>1
if _rc!=0 {
 set obs `=_N+1'
 su hhid, meanonly
 loc fake=r(max)+1
 replace hhid=`fake' in l
 su iid, meanonly
 expand `r(max)' in l
 bys hhid: replace iid=_n if hhid==`fake'
 fillin hhid iid
 drop if hhid==`fake'
 }
bys hhid (iid): g fathered=grade[fatherid]
bys hhid (iid): g mothered=grade[motherid]
cap drop if  _fillin==1
cap drop _fillin
li, noo clean


On 8/16/07, Prabal Kr. De <contactprabal@yahoo.com> wrote:
> Hi!
>   I have a household survey dataset which gives
> householdid (hhid) individual id (iid) and
> corresponding ids for father and mother. Therefore the
> data looks like
>
> hhid    iid     fatherid        motherid        grade_completed
> 1001    1       .       .       6
> 1001    2       .       .       5
> 1001    3       1       2       3
> 1001    4       1       2       3
> 1002    1       .       .       5
> 1002    2       .       .       6
> 1002    3       1       2       8
> 1002    4       .       .       8
> 1002    5       3       4       1
>
> I want to create two variables: fatheredu (father's
> education) and motheredu (mother's education)
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