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st: RE: discriminatory ability between typing systems


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: discriminatory ability between typing systems
Date   Mon, 16 Aug 2004 10:15:38 +0100

There are males, females and cyborgs of 
indeterminate sex on this list, so the 
address "Sir" is not advised. 

Simpson's index has been programmed in 
Stata as such in the program -ineq- 
which is downloadable from SSC. That index 
is based on summing the squares of 
probabilities; sometimes people then 
take the complement or the reciprocal 
of that sum. Identical or similar indices
had been invented before, or were invented 
after, Simpson published on this in 1949. He 
himself got the idea from A.M. Turing 
but could not say so because their contact was
work together on code-breaking in WWII. 
Other names associated with this index
are those of Gini and Herfindahl, although 
conversely the name of Gini has been 
associated with several other measures. 
I believe that geneticists refer to this 
as heterozygosity. 

In short, the keyword to search under
is probably not Simpson, but inequality: 
various versatile programs exist from 
S. Jenkins, P. van Kerm and others.  

This same Simpson is the person after whom 
Simpson's paradox has been named, although 
it was identified earlier by G.U. Yule 
and even earlier by K. Pearson (and ...).

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

Remi
 
> Sir,
>  
> How can I test the discriminatory ability between two 
> bacterial genotypes typing systems ?
> I have heard about an application of the Simpson's index of 
> diversity but
> didn't found anything in stata under this denomination. Is 
> there anything to
> do with the hierarchical cluster analysis and what in this case?

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