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RE: st: trouble using _n-1


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: trouble using _n-1
Date   Tue, 25 Nov 2008 17:19:43 -0000

Joao doesn't mean what he says. _N-1 is the subscript of the next to
last observation in a group. _n-1 is the subscript of the previous
observation. 

I doubt that, even if corrected for this typo, this is what Joseph
wants. It just checks whether the previous value was the same or
different. Joseph wants to measure reliability, a different though
tangentially related story. 

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

Joao Ricardo F. Lima

I think that this can do the trick:

by idcode: assert var1-var1[_N-1]==0

2008/11/25 Joseph Wagner <joseph.wagner@wright.edu>:

> I wish to use the program -concord- to perform an interrater
reliability for
> a rater.  The data is arranged as such:
>
> idcode      date    var1   var2
> --------------------------------------------
> person1   date    var1   var2
> person1   date    var1   var2
> person2   date    var1   var2
> person2   date    var1   var2
>
>
> there are too many variables and observations for me to -reshape- wide
so I
> thought that I could try this:
>
> bysort idcode date: concord var1 var1[_n-1]      since the data is
arrayed
> as pairs of observations which I wish to compare
>
> but instead of working I get the following error: "_n unknown weight
type"
>
> Am I forced to try some sort of piecewise -reshape- (sets of
variables) or
> am I just doing this all wrong?

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