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RE: st: item response


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: item response
Date   Mon, 7 Jul 2003 09:29:00 +0100

dpan@duke.edu
 
> > I am trying to create a weight variable to use with the 
> gllamm command,
> > but I just can't get it to work. Here is the problem: I 
> have the data in
> > long format looking like this:
> > 
> > subj_id         item_number     item_response
> > 1               1               0
> > 1               2               1
> > 1               3               0
> > 2               1               1
> > 2               2               1
> > 2               3               0
> > 
> > I am trying to create a weight variable that represents 
> the number of
> > subjects with the same item_response pattern, meaning the 
> same responses
> > for all items within an individual.

SamL
 
> In Stata 7 I believe the -contract- command is what you would use.

I don't think -contract- helps without a prior -reshape-. 
I would do this:  

reshape wide item_response, i(subj_id) j(item_number) 
bysort item_response* : gen weight = _N 


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

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