----- Forwarded
message from "F.
James Rohlf"
Date: Mon, 25 Jun
2012 11:54:07 -0400
From: "F. James Rohlf"
Reply-To: ro...@life.bio.sunysb.edu
Subject: RE: MANOVA with 3D landmark data
To:
morphmet@morphometrics.org
Note that relative
warp scores and the “PC scores obtained after projecting the Procrustes variables on a
euclidean space”
are identical if done correctly.
Goodall’s F-test
should not normally be used when analyzing real data. That test is based on far
too many assumptions. Best to use a permutation test.
----------------------
F. James Rohlf,
John S. Toll Professor, Stony Brook University
The
much revised 4th editions of Biometry and Statistical Tables are now
available:
http://www.whfreeman.com/Catalog/product/biometry-fourthedition-sokal
http://www.whfreeman.com/Catalog/product/statisticaltables-fourthedition-rohlf
P Please consider the
environment before printing this email
From:
morphmet_modera...@morphometrics.org
[mailto:morphmet_modera...@morphometrics.org]
Sent: Monday, June 25,
2012 6:41 AM
To: morphmet@morphometrics.org
Subject: MANOVA
with 3D landmark data
----- Forwarded message from lia betti
-----
Date: Wed, 20 Jun 2012 09:14:57 -0400
From: lia betti
Reply-To: lia betti
Subject: MANOVA with 3D landmark data
To: "morphmet@morphometrics.org"
Dear all,
I'm trying to test for
sexual dimorphism in shape in different populations, and I would like to do a
MANOVA to test for significant effects of sex, of population, and the
interaction between the two variables. I am using 3D landmark data, and I
realise that the Procrustes coordinates I obtain after Procrustes
superimposition are in a non-euclidean space, and therefore unsuitable for
normal MANOVA. I read that I can use relative warps as data to input in my
MANOVA, and solve the problem this way, but I would prefer to use either the
Procrustes variables, or the PC scores obtained after projecting the Procrustes
variables on a euclidean space (because I then proceed to use Procrustes
variables to estimate indices of sexual dimorphism).
My questions are:
1) Can I apply a normal MANOVA on
the PC scores, given that they are in Euclidean space? I haven't found any paper
or book mentioning this method, and I don't understand
why.
2) I think I could in principle
use Goodall's F test as an alternative to MANOVA on the Procrustes variables,
but MorphoJ specifies that the Procrustes ANOVA run by the program is
suitable only for studies of asymmetry or inter-observer error. Again, I am not
sure why. In R, the function for this test is again mentioned only in
relation to studies of fluctuating asymmetry. Is there a software I can use
to run this test to check for significant effects of sex and
population?
Thanks!
Lia
email: liabe...@yahoo.it
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