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Re: st: Unique dyads


From   Nick Cox <njcoxstata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Unique dyads
Date   Thu, 14 Apr 2011 22:01:32 +0100

I wrote something on this

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

Whether the UCLA FAQ came first I don't know. I wasn't aware of it
when I wrote.

That aside, I don't follow your detail but guess that there is just
one key point: if "partner A - partner B" is not equivalent to
"partner B - partner A", as for example if the first partner is
exporter and the second importer, then

egen id = group(partnerA partner B)

should suffice for unique identifiers.

Nick

On Thu, Apr 14, 2011 at 7:29 PM, emanuele mazzini
<madsoenistata@gmail.com> wrote:

> I am using an unbalanced dyadic panel dataset for which I need to
> generate an unique dyad id. I looked at this help:
> http://www.ats.ucla.edu/stat/stata/faq/dyad_ids.htm but the
> suggestions I found here do not seem to work in my dataset. In
> particular, the example shows that there is a certain symmetry, so
> that the couple for which a=1 and b=5 is the same couple for which a=5
> and b=1. Hence the couple considered gets the same value for the
> variable dyad. But this does not work in my dataset because the couple
> that gets a given value for the variables a and b is not the same
> couple that gets the same values for b and a.
> I can be more clear with the following example, which will be in terms
> of countries, as in my dataset. Suppose I consider the couple USA and
> GBR and I apply the suggested procedure. Then when the couple is:
> USA-GBR i got a=1 and b=75
>
> but when I consider the reverted couple, i.e GBR-USA, i got a=46 and
> b=90, which are absolutely not the same values, as the help i read
> suggest.
>
> Anyone can please help me to understand why this is happening or has
> an alternative way to proceed to get an unique dyad-id identifier?
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