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Re: st: aggregate identical observations


From   Ulrich Kohler <kohler@wz-berlin.de>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: aggregate identical observations
Date   Fri, 12 Dec 2003 13:11:37 +0100

How about:

by pref1 pref2, sort: replace wgt = sum(wgt)
by pref1 pref2: keep if _n == _N

regards
uli

Dietrich Drüner wrote:
> I need to aggregate the number of observations in my data set when they
> have identical values on two variables AND I need to sum up the values of a
> third variable so that it remains the same for the reduced data set. I will
> try to illustrate this and also describe the substantial problem:
>
> my initial data matrix looks like this:
>
> act	wgt	pref1	pref2
> 1	4	100	0
> 2	5	33	0
> 3	3	33	50
> 4	3	100	50
> 5	10	33	0
> 6	10	33	100
> 7	5	33	50
> 8	3	33	50
> 9	10	33	50
> 10	2	33	50
> 11	5	33	0
> 12	5	33	50
> 13	8	33	50
> 14	4	100	0
> 15	10	33	50
> 16		100	70
> 17		100	70
>
> sum	87
>
> The first variable is the number of my actors (the 15 EU member states plus
> the European Commission and the European Parliament). The second variable
> is the voting weights of the member states. The third and fourth variables
> are preferences of the actors in two dimensions. Many of the actors have
> identical preference profiles that I need to aggregate.
>
> The result of this aggregation should look like this:
>
> act	wgt	pref1 pref2
> 1	8	100	0
> 2	20	33	0
> 3	46	33	50
> 4	3	100	50
> 5	10	33	100
> 6		100	70
>
> sum	87
>
>
> How can I do this in Stata (7)?
>
> Thank you!
>
> Regards,
>
> Dietrich.
>
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Dietrich Drüner
> Schneckenburgstr. 24
> D - 78467 Konstanz
>
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>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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>
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-- 
kohler@wz-berlin.de
+49 (030) 25491-361


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