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Re: st: How to identify siblings


From   Grethe Søndergaard <dkstatstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: How to identify siblings
Date   Fri, 18 Jun 2010 10:36:57 +0200

Thank you to both of you for your responses.
It has given me some inspiration of how to manage the data. I am still
hoping to compare more than two siblings in a family because otherwise
my dataset will become quite small (I only want to compare siblings of
the same gender, who have an age difference of maximum 5 years, and
who are discordant on marital status). I realize this might be
complex, but will hopefully find the way to do it.


2010/6/16 Nick Cox <n.j.cox@durham.ac.uk>
>
> For related technique, see
>
> FAQ     . . . . . . . . . . . . . . . . . . . . . . How can I create dyad IDs?
>        . . . . . . . . . . . . . . . . . .  UCLA Academic Technology Services
>        4/10    http://www.ats.ucla.edu/stat/stata/faq/dyad_ids.htm
>
> SJ-8-4  dm0043  . Tip 71: The problem of split identity, or how to group dyads
>        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
>        Q4/08   SJ 8(4):588--591                                 (no commands)
>        tip on how to handle dyadic identifiers
>
> Nick
> n.j.cox@durham.ac.uk
>
> Maarten buis
>
> --- On Wed, 16/6/10, speciale speciale wrote:
> > I have a dataset containing information on a population
> > born in 1980-1990, and some of the persons in the dataset are
> > siblings. I am interested in doing some descriptive analyses, where I:
> >
> > - Compare full brothers with an age difference of maximum five years
> >
> > - Compare full sisters with an age difference…
> >
> > - Compare half brothers with an age difference..
> >
> > - Compare full sister with an age difference…
> >
> > I only wish to compare siblings who are discordant on
> > marital status in order to find out if this has any
> > impact on later health outcomes.
> >
> > The dataset includes the following information:
> >
> > Person ID
> >
> > Gender
> >
> > Mother ID
> >
> > Father ID
> >
> > Age/day of birth of the person
> >
> > Marital status
> >
> > Different health indicators
> >
> > Etc..
> >
> >
> > So my questions are:
> >
> > -How to identify who in the dataset are half siblings /
> > full siblings?
> >
> > -How is it possible to handle the fact that one person
> > might have both
> > several half and full siblings - and make pairwise
> > comparisons of each
> > of these pairs (but only if they are  of the same gender
> > and have a
> > age-difference of maximum 5 years)?
>
> I would stick with families consisting of only 2 children,
> this makes things easier for you (and as the "official" reason
> you can say that this way you control for the possible
> confounding effect of family size)
>
> You can select full siblings by making sure they have the
> same father and mother. The line -egen famid = group(fid mid)-
> creates a unique identifier for people who share the same
> parents.
>
> If you want to compare sibs it is often convenient to
> -reshape- your data so that you have two variables: in
> this case one for the first born and one for the second
> born. In your case you probably want to have marital
> status as your -j()-
>
> *----------------- begin example -------------------
> drop _all
> input id byr fid mid x
> 1  1977 1 1 1
> 2  1979 2 1 5
> 3  1982 1 1 4
> 4  1966 3 2 6
> 5  1671 3 2 4
> 6  1973 4 3 2
> 7  1695 5 4 3
> 8  1967 5 4 4
> 9  1969 5 4 7
> end
>
> egen famid = group(fid mid)
> bys famid (byr) : gen birthorder = _n
> bys famid (byr) : gen size = _N
>
> keep if size == 2
>
> reshape wide x id fid mid byr, i(famid) j(birthorder)
> *--------------------- end example ------------------
> (For more on examples I sent to the Statalist see:
> http://www.maartenbuis.nl/example_faq )
>
>
> *
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