Burak,
I think your question is simpler than the suggestions of NMDS. One
approach, let's say you dissimilarity matrix is called demodis
> demodis2 <- as.matrix(demodis) # make a full matrix copy
> is.na(diag(demodis2)) <- TRUE # ignore the dissimilarity of a
# plot to itself
> apply(as.matrix(demodis),1,mean) # calcualte the mean dissimilarity
# of every plot to the others
This is all done as part of function disana() in package labdsv along
with some other simple dissimilarity analyses.
Dave Roberts
On 11/23/2010 01:09 PM, Pekin, Burak K wrote:
Hello, I want to rank the dissimilarity of sites based on their species
composition. For example, I would like to be able to say that site A is less
similar in composition to the other sites than site B is similar to the other
sites. I could do a cluster analysis and look at which sites are less closely
clustered.
It would be even better if I could come up with a quantitative scale rather
than a relative ranking that would give a value for each site based on its
relative dissimilarity to the rest of the sites. So site A might receive a 90
out of 100, whereas site B and C might receive a 60 and a 50 indicating the
rank as well as 'relative quantity' of dissimilarity for each site.
Thanks,
Burak
--------------------------
Burak K. Pekin, PhD
Postdoctoral Research Associate
Purdue University
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