Brett:
Darroch and Mosimann (1985) is a frequently-cited paper that talks
about scale adjustment for both PCA and CVA. They use "log-shape" data
that are ln-transformed ratios. That paper should be a useful starting point.
Darroch JN & Mosimann JE (1985) Canonical and principal components of
shape. Biometrika 72:241-252.
Good luck,
Tim Cole
At 10:09 AM 5/17/2004 -0400, you wrote:
>Dear morphometrician,
>
>I have recently reviewed 3 genera of catsharks that display a great deal
>of morphological conservation within the genera, however, there is also
>prominent sexual dimorphism present (profoundly so in some species). There
>is quite a bit of shape variation between juveniles and adults, in one
>genus in particular, but I think that the shape variation is being
>obscured by the size component.
>
>I have a sizeable morphometric data set (# measures >> # taxa & specimens)
>and have used principal components analysis on the raw data to explore
>shape variation within each of the genera (not between). The first
>component was always a general component and accounted for more than
>85-90% of the variation in most instances, therefore the bipolar
>components only contributed relatively little to the overall shape
>variation resulting in crowded PCA plots.
>
>The main reference I have used for the analyses to date has been
>'Pimental. 1979. Morphometrics. The multivariate analysis of biological
>data' however, it doesn't deal with size correction. Can anyone suggest a
>review that deals with size correction, or can I convert my data to ratios
>and then log transform the data?
>
>I am also looking for reviews of canonical discriminant functions analysis
>and stepwise discriminant function analysis in an attempt to quantitate
>differences between species within a genus.
>
>Thanks for your help.
>
>Brett
>
>************************************
> Brett Human
> Shark Researcher
> 27 Southern Ave
> West Beach SA 5024
> Australia
> 61 8 8356 6891
> [EMAIL PROTECTED]
> ************************************
>
>
>
>==
>Replies will be sent to list.
>For more information see http://life.bio.sunysb.edu/morph/morphmet.html.
Theodore M. Cole III, Ph.D.
Department of Basic Medical Science
School of Medicine
University of Missouri - Kansas City
2411 Holmes St.
Kansas City, MO 64108
USA
Phone: (816) 235 -1829
FAX: (816) 235 - 6517
e-mail: [EMAIL PROTECTED]
www: http://c.faculty.umkc.edu/colet
==
Replies will be sent to list.
For more information see http://life.bio.sunysb.edu/morph/morphmet.html.
