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Re: st: Question on data manipulation


From   Susanne und Ulrich Kohler <suli.kohler@web.de>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Question on data manipulation
Date   Fri, 21 Oct 2005 13:15:14 +0200

On Friday 21 October 2005 11:48, Andre pierre wrote:
> I have a question, for which the answer might be simple, but I did not find
> it yet.
> I am working on a datset that contains information on innovating firms. My
> question might be more understandable with the following example:
> Firm 1 has 3 innovations (A, B and C). A and B have one caracteristic in
> common (x); B and C have another caracteristic in common (g), while
> Innovation D does not have the same caracteristic as any of the other
> innovations.
> I would like to create a dummy that takes the value one if an invention by
> a given firm has at least one caracteristic in common with one of the other
> innovations by the the same firm. My question is how can I get this dummy?
>
> Firm; innovation; carateristic; dummy
> 1; A; x; 1
> 1; A; y; 1
> 1; A; z; 1
> 1; B; x; 1
> 1; B; g; 1
> 1; C; g; 1
> 1; D; f; 0

. by firm (charateristic): gen dummy = _N > 0
. by firm innovation (dummy): replace dummy = dummy[_N]

-- 
kohler@wz-berlin.de
+49 (0)30 25491-361
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