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st: RE: summation (+ absolute value) formula


From   "Scott Merryman" <smerryman@kc.rr.com>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: summation (+ absolute value) formula
Date   Tue, 7 Nov 2006 17:01:21 -0600

bysort id (t): gen foo = sum(abs((pip - l.pip)/l.pip))
replace foo = . if t  <   t[_N -2]


Scott

> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-
> statalist@hsphsun2.harvard.edu] On Behalf Of west--@libero.it
> Sent: Tuesday, November 07, 2006 3:22 PM
> To: statalist
> Subject: st: summation (+ absolute value) formula
> 
> I need some help, thank you in advance.
> 
> Given a variable (taken from a set of n variables in a panel), called
> "Pippo", I need to compute the following formula:
> 
> Somma_(i=t-2 to t) of Absolute_value[(Pippo(i) - Pippo(i-1))/Pippo(i-1)]
> 


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