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May 2005


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Richard Wright <[log in to unmask]>
Reply To:
Classification, clustering, and phylogeny estimation
Thu, 26 May 2005 15:51:45 +1000
text/plain (76 lines)
I should have written: "I have a series of linear measurements of bones . . ." They in fact include several measurements of breadth and thickness.

I wonder why the sum of all measurements should be such an unusual choice. 

Richard Wright

>Subject: Re: size
>   From: "F. James Rohlf" <[log in to unmask]>
>   Date: Wed, 25 May 2005 22:23:00 -0400
>     To: [log in to unmask]
>There are many methods that have been proposed. The simplest is to express
>them as ratios of some measure of size - which gets back to the original
>question as there are many ways to express size. The sum of all the
>measurements is a pretty unusual choice but it often may not matter much in
>practice because the measurements are usually very highly correlated.
>F. James Rohlf, Distinguished Professor & Graduate Program Director
>State University of New York, Stony Brook, NY 11794-5245
>> -----Original Message-----
>> From: Classification, clustering, and phylogeny estimation 
>> [mailto:[log in to unmask]] On Behalf Of leo horseman
>> Sent: Wednesday, May 25, 2005 10:03 PM
>> To: [log in to unmask]
>> Subject: 
>> I do not have a citation for you; however, I am interested in 
>> the question.  
>> I must admit to being baffled.  Why include size measurements 
>> in your analysis at all, unless somehow the measurement of 
>> shape is derived from the size measurement.  If you've 
>> measured only bone lengths, which surely would vary greatly 
>> in size, then how did you arrive at a shape measurement?
>> M.C.
>> >From: Richard Wright <[log in to unmask]>
>> >Reply-To: "Classification, clustering, and phylogeny 
>> estimation"            
>> >   <[log in to unmask]>
>> >To: [log in to unmask]
>> >Date: Mon, 23 May 2005 12:06:54 +1000
>> >
>> >This is a question about size and shape in morphometric studies.
>> >
>> >I have a series of measurements of bone lengths in individuals that 
>> >vary greatly in size. I want to consider similarities and 
>> differences 
>> >between the individuals solely in terms of shape. To remove 
>> differences 
>> >in absolute size I have taken each individual, summed all the 
>> >measurements for that individual, and then divided each 
>> measurement by that sum.
>> >
>> >This is an intuitively simple method. Some years ago I read a 
>> >recommendation about using it. Now an editor is asking me to cite a 
>> >reference to the use of the method. Unfortunately I cannot recollect 
>> >where I saw it advocated.
>> >
>> >Can anybody help?
>> >
>> >I know that there are various alternative methods for 
>> eliminating size 
>> >in multivariate morphometric work, such as eliminating the first 
>> >principal component if that is one of general size. However 
>> my question 
>> >is not about the competing merits of size/shape methodologies in 
>> >general. This is a specific request for a citation of the 
>> approach outlined above.
>> >