Hello there,


Here's a question regarding p-values on clusters produced by hierarchical
cluster analysis.  A web search led me to the program pvclust to tackle this
problem.  But when I run the problem I get strange results.  The 'AU'
(approximately unbiased) p-values are very different from the 'BP' values
(ordinary boot-strap) p-values. The AUs commonly are in the 80-100 range
where the BPs are in the 0-10 range!

One clue as to what might be happening is a warning from R:  "inappropriate
distance matrices are omitted in computation" for different r values.



Perhaps my data is not really well suited for this analysis?  I have
presence-absence (0,1) data of 32 species in 60 different locations.  It is
noticeable that the difference between AU and BP is not as bad when I try to
cluster by species, as when I try to cluster by location.



Any comments on this issue would be very much appreciated.  Are there any
other programs that might be able to produce similar results?  Should I try
to run the bootstrap analysis myself in R, and is there a good introductory
test to tell me how to do this?



With thanks and best wishes,



Eben



Eben Goodale

NSF International Postdoctoral Fellow

University of Colombo, Sri Lanka

eben.goodale@gmail.com

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