(Fwd) G-Fit index in PAUP (fwd) ($te)

Michael Moeller M.Moeller at RBGE.ORG.UK
Tue Jul 23 08:56:35 CDT 2002

Hello Davide,

Now that PAUP* deals in multiple optimality criteria the gfit option
has been moved under the pscores command.  For example:

pscores 1/gfit;

Will give you the gfit measure for the first tree in memory.

The menu equivalent is Trees > Tree scores ... > parsimony ...

The measure is pretty straight forward.

For all characters, sum: (k+1)/(s+k+1-m)

k = constant of concavity
s= length (number of steps) required by the characters on the tree
being evaluated
m= minimum amount of change that the character may show on any conceivable tree

Increasing k simply changes the relationship between the consistency
and the weight for a given character, such that less consistent
characters are down-weighted less with larger values of k.

The method is that of Goloboff (1993) and is described in greater detail in:

Goloboff, P. A.  1993.  Estimating character weights during tree
search.  Cladistics 9: 83-91.

Let me know if I need to go into greater detail.


>---------- Forwarded message ----------
>Date: Thu, 18 Jul 2002 08:49:36 BST
>From: Michael Moeller <M.Moeller at rbge.org.uk>
>To: James Wilgenbusch <jwilgenb at onyx.si.edu>
>Subject: (Fwd) G-Fit index in PAUP
>------- Forwarded message follows -------
>Date sent:             Wed, 17 Jul 2002 22:21:28 +0200
>Send reply to:         Davide Sassi <d.sassi at MAIL.NET1.IT>
>From:                  Davide Sassi <d.sassi at MAIL.NET1.IT>
>Subject:               G-Fit index in PAUP
>To:                    TAXACOM at USOBI.ORG
>Can anyone out there explain me please how is calculated in PAUP the index
>G-FIT which appears in CHARACTER DIAGNOSTICS (an option of DESCRIBETREES)?
>Thank you in advances,
>Davide Sassi
>via san Rocco 17
>e-mail: d.sassi at mail.net1.it
>------- End of forwarded message -------
>Dr. Michael Moeller
>Cytologist & DNA Analyst
>Royal Botanic Garden Edinburgh
>20A Inverleith Row
>Edinburgh EH3 5LR
>Scotland (UK)
>Tel.: +44 (0) 131 248 2886
>Fax.: +44 (0) 131 248 2901

Jim Wilgenbusch
paup-support at csit.fsu.edu

Computational Science & Information Technology
Florida State University
400 Dirac Science Center Library
Tallahassee, Florida 32306-4120

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