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Re: st: product function


From   Roger Newson <roger.newson@kcl.ac.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: product function
Date   Tue, 25 May 2004 18:06:01 +0100

At 11:43 25/05/04 -0500, Dimitriy V. Masterov wrote:
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.
One way might be to calculate logs and then to use the -sum()- function.

Roger


--
Roger Newson
Lecturer in Medical Statistics
Department of Public Health Sciences
King's College London
5th Floor, Capital House
42 Weston Street
London SE1 3QD
United Kingdom

Tel: 020 7848 6648 International +44 20 7848 6648
Fax: 020 7848 6620 International +44 20 7848 6620
  or 020 7848 6605 International +44 20 7848 6605
Email: roger.newson@kcl.ac.uk
Website: http://www.kcl-phs.org.uk/rogernewson

Opinions expressed are those of the author, not the institution.

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