-------- Original Message -------- Subject: Re: MorphoJ problem: erroneous canonical coefficients? Date: Wed, 29 Feb 2012 06:38:43 -0500 From: Chris Klingenberg <c...@manchester.ac.uk> Reply-To: c...@manchester.ac.uk Organization: University of Manchester To: morphmet@morphometrics.org Dear Louis There is nothing erroneous with the canonical coefficients provided by MorphoJ, as far as I know. The way you phrase your query suggests that you expect that the shape changes associated with canonical variates (CVs) are just a scaled version of the CV coefficients, as it holds for principal components. This expectation is mistaken, because it misses the crucial difference that CVs are not computed in shape (tangent) space itself, but in a transformed space. This problem has been extensively discussed in geometric morphometrics. The computations of shape changes associated with CVs that are used in MorphoJ are based on the solution proposed by Rohlf et al. (1996): Rohlf, F. J., A. Loy, and M. Corti. 1996. Morphometric analysis of Old World Talpidae (Mammalia, Insectivora) unsing partial-warp scores. Syst. Biol. 45:344–362. More discussion on transformed spaces and discriminant/canonical variate analysis can be found here: Klingenberg, C. P., and L. R. Monteiro. 2005. Distances and directions in multidimensional shape spaces: implications for morphometric applications. Syst. Biol. 54:678–688. I hope this is useful. Best wishes, Chris On 2/27/2012 5:23 PM, morphmet wrote:
-------- Original Message -------- Subject: MorphoJ problem: erroneous canonical coefficients? Date: Thu, 23 Feb 2012 08:18:03 -0500 From: Louis Boell <lbo...@evolbio.mpg.de> To: morphmet@morphometrics.org Dear colleagues, I am encountering a peculiar problem in MorphoJ: after performing CVA, the Canonical Coefficients given in the results do not correspond at all to the vector lengths in the lollipop shape change graphs. Either the graphs or the Coefficients appear to be erroneous, because they contradict each other. This only happens with CVA, not with PCA, for which the results are nicely congruent. Did anyone else encounter this? Any explanation? Thanks for any help Best regards, Louis
-- *************************************************************** Christian Peter Klingenberg Faculty of Life Sciences The University of Manchester Michael Smith Building Oxford Road Manchester M13 9PT United Kingdom Telephone: +44 161 275 3899 Fax: +44 161 275 5082 E-mail: c...@manchester.ac.uk Web: http://www.flywings.org.uk Skype: chris_klingenberg ***************************************************************
