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Re: st: Fischer Exact Test again


From   "Neil Shephard" <mdeasnds@fs1.ser.man.ac.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Fischer Exact Test again
Date   Tue, 11 Jun 2002 09:16:38 +0100

Although not implemnted in Stata there is a program called 
CLUMP written by Dave Curtis and Pak Sham which is "designed 
to  assess the significance of the departure of observed values in a 
contingency table from the expected values conditional on the 
marginal totals."

The program can deal with 2xN tables and produces novel, 
maximised, chi-squared statistics through the "clumping" of 
columns together .  These inflated chi-squared values are 
assessed for significance through Monte Carlo methods.

The original reference is

Sham PC, Curtis D (1995) Monte Carlo tests for associations 
between disease and alleles at highly polmorphic loci.  Annals of 
Human Genetics 59 pp97-105

CLUMP is available for download from Dave Curtis' web-page at

http://www.mds.qmw.ac.uk/statgen/dcurtis/software.html

Whilst it was orignally designed for analysing genetic data the 
methods should be applicable to your problem and provide an 
alternative to Fisher's exact p-values.  (It's also pretty fast!!!).

Regards

Neil

Neil Shephard
Genetics Statistician
ARC Epidemiology Unit, University of Manchester
neil.shephard@man.ac.uk
neil.shephard@mindless.com

"Contrariwise, if it was so, it might be; and if it
were so it would be; but as it isn't, it ain't. That's
logic" - Tweedledee (Alice Through the Looking Glass)
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