-------- Original Message -------- Subject: RE: outlines analysis Fourier coefficients Date: Wed, 27 Feb 2008 15:09:24 -0800 (PST) From: F. James Rohlf <[EMAIL PROTECTED]> Reply-To: <[EMAIL PROTECTED]> Organization: Stony Brook University To: <[email protected]> References: <[EMAIL PROTECTED]>
Matrices of partial warp scores and of EFA scores (usually called "coefficients" but that is not really correct because they are the projections of your data onto vectors that define each harmonic) are both multivariate data sets. They can be treated in similar ways in multivariate analyses - just with different interpretations because they are for different shape variables and need not give the same results for the same sets of specimens. ========================= F. James Rohlf Distinguished Professor, Stony Brook University http://life.bio.sunysb.edu/ee/rohlf
-----Original Message----- From: morphmet [mailto:[EMAIL PROTECTED] Sent: Wednesday, February 27, 2008 5:37 PM To: morphmet Subject: Re: outlines analysis Fourier coefficients -------- Original Message -------- Subject: Re: outlines analysis Fourier coefficients Date: Wed, 27 Feb 2008 06:37:32 -0800 (PST) From: Matthew Burton-Kelly <[EMAIL PROTECTED]> To: [email protected] References: <[EMAIL PROTECTED]> Hello all, The quoted message is from a couple months back, but I would like to clarify for my own sanity. I am attempting to calculate disparity based on elliptical Fourier coefficients--am I correct in thinking that I can use MD=Tr{S}* on my elliptical Fourier coefficients in the same way I could on partial warp scores? *Morphological Disparity = Trace(variance-covariance matrix) Thanks, Matt Burton-Kelly On 25 Nov, 2007, at 9:36 AM, morphmet wrote: > The same considerations apply to any multivariate study (conventional > variables, partial warp scores, or scores on Fourier harmonics). One > can > use exploratory methods such as PCA or cluster analysis with any > sample > size but in order use methods that look at difference among groups > relative to within-group variability one needs the degrees of > freedom of > the within-group covariance matrix to be greater than the number of > variables. With fewer observations the within-group covariance matrix > will be singular. This rule gives a minimum sample size but for > reliable > results the sample size should, of course, be much larger. This makes > the use of a number of standard multivariate methods impractical when > using many harmonics or many landmarks so that less powerful methods > have to be used. > > ------------------------ > F. James Rohlf, Distinguished Professor > Ecology & Evolution, Stony Brook University > www: http://life.bio.sunysb.edu/ee/rohlf > > >> -----Original Message----- >> From: morphmet [mailto:[EMAIL PROTECTED] >> Sent: Sunday, November 25, 2007 6:44 AM >> To: morphmet >> Subject: outlines analysis Fourier coefficients >> >> Dear morphometricians. >> >> I would like to know, if it is possible... >> How to calculate the number of harmonics, for the estimation of >> Fourier >> coefficients, depending the number of individuals sampled. >> Some formulae. >> I know this formulae (k-1)/2 or (k/2, K=numer of points on the >> outlines. >> I know that the number of harmonics depends on the degree of >> recostrucion of the original structure, but what about the number of >> individual. >> >> Thanks >> >> Ang?lica Cuevas >> >> ----------------------------------------------------------------- ------ >> - >> >> Comparte video en la ventana de tus mensajes (y tambi?n tus fotos >> de >> Flickr). >> Usa el nuevo Yahoo! Messenger versi?n Beta. >> Visita http://e1.beta.messenger.yahoo.com/ >> >> -- >> 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 > ----------------------------- Matthew Burton-Kelly Graduate Student Department of Geology and Geological Engineering University of North Dakota (802) 922-3696 [EMAIL PROTECTED] http://uweb.und.nodak.edu/~matthew.burton.kelly/ -------------------------------------------- "About thirty years ago there was much talk that geologists ought only to observe and not theorize; and I well remember someone saying that at this rate a man might as well go into a gravelpit and count the pebbles and describe the colors. How odd it is that anyone should not see that all observation must be for or against some view if it is to be of any service!" -Charles Darwin, in an 1861 letter to Henry Fawcett. -- Replies will be sent to the list. For more information visit http://www.morphometrics.org
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