Hi all, in literature, several people have been using Procrustes distances as the data for a cluster-analysis, more specifically UPGMA. When doing so, the Procrustes distances between the consensus configurations of each OTU are used to calculate a tree based on shape similarities between the consensusses. However, when using Procrustes distances, one is ignoring possible differences in the amount of within-group variation (or is assuming it is the same for all the OTUâs), not? The Procrustes distance between the means of three groups can be the identical, but because of overlapping variations within two of them, the shape distance will in many cases be much lower.
So my question is, whether it is not wiser to use the Squared Mahalanobis distances of a canonical variate analysis (based on weight matrix), as a measure of shape distance between group means for a UPGMA, as this does take into account the amount of within-group variation (and as I understood even standardises it). Does this make sense or is there some mathematical-statistical pitfall behind it? cheers Dominique Adriaens Prof. Dr. Dominique Adriaens Ghent University Evolutionary Morphology of Vertebrates & Zoology Museum K.L. Ledeganckstraat 35, B-9000 Gent BELGIUM tel: +32 9 264.52.19, fax: +32 9 264.53.44 E-mail: [EMAIL PROTECTED] URL: http://www.fun-morph.ugent.be/ http://www.zoologymuseum.ugent.be/ -- Replies will be sent to the list. For more information visit http://www.morphometrics.org
