-------- Original Message -------- Subject: RE: Symmetry in MorphoJ Date: Fri, 29 Jul 2011 03:22:36 -0400 From: J.C. van Rijssel <[email protected]> To: <[email protected]> Dear Chris and Ruth, Thank you for your swift and useful replies! It is now clear to me! @Ruth, with "all individuals grouped together" I meant grouping like in a DFA where you compare two different groups as well e.g. left and right (what would make no sense when testing for directional asymmetry, but clearly this is not the case with the procrustes Anova) Best regards, Jacco van Rijssel -----Original Message----- From: morphmet [mailto:[email protected]] Sent: donderdag 28 juli 2011 20:20 To: morphmet Subject: Re: Symmetry in MorphoJ -------- Original Message -------- Subject: Re: Symmetry in MorphoJ Date: Wed, 27 Jul 2011 08:18:26 -0400 From: Chris Klingenberg <[email protected]> Reply-To: [email protected] Organization: University of Manchester To: [email protected] Dear Jacco
1. What does a significant outcome of the term "individual" mean? Does it mean that there is individual variation between samples in
asymmetry? This is not too exciting -- it means that the variation of the shapes among individuals (the left/right average) exceeds its error component (that in turn depends on whether you look at matching or object symmetry).
2. What does a significant outcome of the term "side" mean? Is there then no symmetry between sides (e.g. left and right)? So are all individuals grouped together? Can we compare this with a paired
t-test?
And if left and right are grouped together, what is than the
difference
with a DFA and a procrustes ANOVA?
There is statistically significant directional asymmetry, i.e. there is a systematic asymmetry of shape.
3. The graphical output of the procrustes Anova shows the one side
minus
the other side (left-right). Is there with this analysis accounted for variation of asymmetry? So in other words, is there accounted for the fact that sometimes distances between landmarks are larger at one
side,
and sometimes at the other side which would equilibrate differences in asymmetry?
This graph shows the *average asymmetry*, that is, the directional asymmetry, in the sample. The graph does not show any variation in asymmetry -- for the variation around this average asymmetry, look at the asymmetry component in the dataset "..., individual values" that is attached to the Procrustes ANOVA in the project tree. For more detailed information, see: Klingenberg, C. P., M. Barluenga, and A. Meyer. 2002. Shape analysis of symmetric structures: quantifying variation among individuals and asymmetry. Evolution 56:1909-1920. http://www.flywings.org.uk/PDF%20files/Evol2002.pdf and Klingenberg, C. P., and G. S. McIntyre. 1998. Geometric morphometrics of developmental instability: analyzing patterns of fluctuating asymmetry with Procrustes methods. Evolution 52:1363-1375. http://www.flywings.org.uk/PDF%20files/Evol1998.pdf Best wishes, Chris
Thanks in advance, /Jacco C. van Rijssel, PhD student/ Section Integrative Zoology Institute of Biology Leiden Leiden University P.O.Box 9505, 2300 RA LEIDEN Room number 6.5.14a The Netherlands Tel: +31(0)71 5274503 Mobile: +31(0)6 41453003 ========================================================= Visiting address: Sylvius Laboratory, Sylviusweg 72, 2333 BE Leiden Website: http://www.science.leidenuniv.nl/index.php/ibl/van_rijssel =========================================================
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