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st: RE: gen a newvar


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: gen a newvar
Date   Mon, 14 Mar 2005 17:26:57 -0000

I am not sure that I understand the reference to _N here. 

With a few guesses it sounds as if you want something 
like this 

bysort id (x) : gen newvar = cond(x[_N] - x[_N-1] <= 7, x[_N-1], x[_N]) 

This will not work with missing values, so you might want 
something more like 

gen byte present = !mi(x) 
bysort present id (x) : gen newvar = <same stuff> if present 
bysort id (newvar) : replace newvar = newvar[1] if mi(x) 

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

Hans J. Baumgartner
 
> My data looks like this:
> 
> id	x
> 1	5
> 1	5
> 1	10
> 1	10
> 1	21
> 1	21
> 1	21
> 2      ...
> 
> I want to generate a newvar with the maximum value of x , 
> which is _N. 
> But if the difference between the largest and the second 
> largest value 
> is <=7, newvar should take the value of the second largest value of x.
 

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