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st: RE: Cumulative Sum by groups


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: Cumulative Sum by groups
Date   Fri, 22 Apr 2005 15:18:32 +0100

bysort ID (year) : gen cusum = _N - _n + 1 

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

Alexander Nervedi
 
> I am looking to implement a group level cumulative sum that 
> starts counting 
> backwards. Any suggestions on how to go about this would be 
> really useful
> 
> data example:
> ID  year  num   cusum
> 1    90      1       2
> 1    91      1       1
> 2    90      1       4
> 2    91      1       3
> 2    92      1       2
> 2    93      1       1
> 3    90      1       1
> 4    90      1       2
> 4    90      1       1
> ...
> 
> I have variables ID year and num, and am trying to create cusum

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