Weights

James Francis Lyons-Weiler weiler at ERS.UNR.EDU
Thu Feb 27 06:37:40 CST 1997


On Thu, 27 Feb 1997, Matt Davey wrote:

> Can anybody actually give me a brief definition/justification for
> reweighting/weighting morphological characters?
>
> Matt Davey
>


Consider the fact that when one decides to not weight morphological (or
molecular) characters, one has decided that a transformation among states
is character i has then same information (and therefore relative
probability) as a transformation among states in character j.  That is, a
decision to use equaly weight is arbitrary, and requires as much
justification as any weight weighting scheme.  See Swofford et al.'s
chapter in Molecular Systematics (2nd ed, Sinauer) for a good discussion
of generalized parsimony.

(Felsenstein (1983); NATO symposium) made the excellent and astute point
that parsimony requires implicit statements about the probability of
character evolution; these probability statements are merely made explicit
under generalized parsimony.


Hope this helps,

James Lyons-Weiler



        Quote taken out of context:
                Date: Tue, 25 Feb 97 12:44:03
                From: Tom DiBenedetto <tdib at umich.edu>
                To: James Francis Lyons-Weiler <weiler at equinox.unr.edu>


                >"I think you are right..."




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