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Message-ID: <A03919E6-7425-11D7-A090-000393DB5846@msu.edu>
Date: 2003-04-21T18:18:18Z
From: Hector L. Ayala-del-Rio
Subject: multiv library

Hi
   I am not sure if this question if appropriate for this forum but here 
it goes.
I was trying to do PCA analysis using the multiv library and I realized 
that this particular library contains 8 methods of PCA which use 
different correlation covariance structures and normalization of the 
data.  When I analyze one particular data set with the 8 different 
methods I get different results in terms of the graphical display and 
percentage of the variance explained.  My question which method is more 
appropriate under what circumstances.  If somebody knows a reference 
that talks about the 8 different methods mentioned in documentation of 
this library please let me know. I am familiar with the differences 
between a correlation and a covariance matrix, but not with the other 
ones.  If you think that I should post this message in a different 
mailing list, please let me know.

Thanks and apologies if there is any information in the archives that I 
did not find :-).

Hector

H?ctor L. Ayala-del-R?o, Ph.D.
Center for Microbial Ecology &
Center for Genomic and Evolutionary Studies
on Microbial Life at Low Temperatures
Michigan State University
545 Plant & Soil Sciences Building
East Lansing, MI 48824-1325
Phone: 517-353-9021
Fax: 517-353-2917