Hi, Just wanted to clarify in this context that in the 2003 paper we used a combination of GPA and EFA just to normalize of the outlines, but statistics were computed on EFA coefficients only.
Martin Martin Friess Musée de l'Homme Département Hommes, Nature, Sociétés 17, place du Trocadéro 75116 Paris France Quoting morphmet <[EMAIL PROTECTED]>: > Hi, > > There is a paper by Friess and Baylac on that (attachment). But I would > suggest to use semilandmarks to describe the outlines - this allows you > to use all the advantages of geometric morphometrics. Also, a > combination of Procrustes coordinates and Fourier descriptors give a > strange shape space. The different variables do not share the same units > and probably do not have comparable variances. > > Of course, Discriminant Function Analysis works better with more > variables - but this does not necessarily mean that additional > information has been added (augmenting random variables would also > increase discrimination). In principal, different types of variables > should not matter for DFA. > > Best, > > Philipp > > > Philipp Mitteroecker > > Department of Anthropology > University of Vienna > Austria > > > On Fr, 2.02.2007, 17:50, morphmet wrote: >> Dear All >> >> I have a question regarding combining two types of morphological >> variables into the same analysis. I have a 3D landmark configuration >> and associated 3D outlines, which are registered in a common >> reference frame (via GPA). I have generated Procrustes variables from >> the landmark configuration and Fourier coefficients from the outline >> data. >> >> A) Does anyone know of a published example where procrustes variables >> have been analysed WITH Fourier coefficients in the same analysis >> (e.g. Principal Components Analysis) and B) If not, can anyone think >> of any reason why these two types of shape variables cannot be >> analysed simultaneously? I ran a dummy test using both variables at >> the same time and found that similar patterns between groups were >> produced with both variable-types, although cross-validated >> classification of groups (using Discriminant Function Analysis) was >> best when both Procrustes and Fourier variables were used together. >> >> Any further comments or suggestions would be greatly appreciated! >> >> Many thanks in advance Noreen [EMAIL PROTECTED] >> >> -- Noreen von Cramon-Taubadel Department of Biological Anthropology >> University of Cambridge The Henry Wellcome building, Fitzwilliam >> street Cambridge CB2 1QH Phone: +44 1223 764719 [EMAIL PROTECTED] >> >> >> >> -- Replies will be sent to the list. For more information visit >> http://www.morphometrics.org >> >> >> > > > -- > Replies will be sent to the list. > For more information visit http://www.morphometrics.org > -- Replies will be sent to the list. For more information visit http://www.morphometrics.org
