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RE: st: Creating variables describing parents' characteristics with parents' ID


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: Creating variables describing parents' characteristics with parents' ID
Date   Tue, 17 Mar 2009 18:10:12 -0000

Bill gave here a solution based on -merge-. 

Those interested in such problems may want to compare with my earlier
and totally different solution. 

<http://www.hsph.harvard.edu/cgi-bin/lwgate/STATALIST/archives/statalist
.0903/date/article-698.html>

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

William Gould, StataCorp LP

Eunsu Ju <juxx0008@umn.edu> writes, 

> I would like to generate a new variable which contains the information
of
> parents, e.g. dad's education.  My data looks like below.
> 
> FID	PID	Var1	Edu	Var3	Dad's FID  Dad's PID  Dad's Edu
> 1001	10	1	3	5	.	        .	
> 1001	20	3	3	2	.		.	
> 1001	30	4	2	3	1001	        10	 3
> 1001	31	8	5	5	1001		10	 3
> 1002	1	2	4	3	.		.	 .
> 1002	10	4	2	1	1002		1	 4
> 1002	20	5	4	2	.		.	 .
> 1002	30	9	3	2	1002		10	 2
> 1002	31	6	1	4	1002		10	 2
> 1002	32	4	2	5	1002		10	 2
> 
> Note: FID = Family ID; PID = Person ID; Edu = Educational attainment
> (Values are randomly assigned, but data structure is similar to the
above.)
>  
> What I want to do is to have the last (far left) column, which is not 
> included in the dataset. (I want to do this kind of works for other 
> variables, e.g. Var1 and Var3.)
> What is the best & simplist way to do this in stata? 
> 
> I think I can do this like the following.
> [...]

Eunsu Ju's plan is exactly right.  He makes step 1, 

> 1) Split the data set into two files so that one file contains Dad's
FID 
>    and Dad's PID, and the other has all others.

more difficult than it needs to be and later leaves doesn't worry about 
something that may not happen, but it's right overall.

Here's the solution, calling Eunsu Ju's original data master.dta.  

<<< snip >>> 

We now have the desired result.  Note that in master, the same dad might

appear more than once.  The dads in step2.dta appear only once, however,
so
that same dad will be spread across the observations in master.
Perfect.


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