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st: RE: product function


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: product function
Date   Tue, 25 May 2004 17:56:19 +0100

You don't need a built-in. This is one way of doing it. 

. set obs 50 
. gen i = _n 
. gen double p = 1 - 1/365 
. replace p = p[_n - 1] * (1 - _n / 365) in 2/l 
. scatter p i 

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

> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu]On Behalf Of Dimitriy V.
> Masterov
> Sent: 25 May 2004 17:43
> To: statalist@hsphsun2.harvard.edu
> Subject: st: product function
> 
> 
> I would like to plot the probability that two people share a 
> birthday as a
> function of the number of people in the room n. The formula is
> 
> 	1-product((366-i)/365,i,1,n)
> 
> In TeX, it would be
> 
> 	1-\dprod\limits_{i=1}^{n}\frac{366-i}{365}.
> 
> If I have a variable n={1,...,50}, how can I define the product within
> Stata? There does not seem to be math function that can do this.
> 
> DVM
> 
> 
> ______________________________________________________________
> _________________
> Dimitriy V. Masterov
> 
> Work:
> Center for Social Program Evaluation
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