nominal characters

Alan Harvey aharvey at AMNH.ORG
Fri Apr 7 11:57:47 CDT 1995

At 8:10 AM 4/7/95, Richard Jensen wrote:
>Ordering of two state characters may be implicit, but unless we know the
>evolutionary origin (e.g., for my example of fruit maturation in oaks:
>annual vs. biennial), we can't be sure of the ordering.  Simply coding
>one as 0 and the other as 1 does not validate the "order."  Whic way is
>it, 1-->0  or 0-->1?  While the order is unchanged, the interpretation is
>quite different.  This will be important for cladistic analyses in which
>the transformation series needs to be included (of course, parsimony
>methods can be applied to unordered data).

I don't mean to nit-pick, but what Richard describes above as the "order"
of a two-state character is in fact its "polarity."  As Maddison, Donoghue
and Maddison (1984) and probably a slew of others have noted, polarity and
ordering are different concepts and need to be treated as such.

Alan Harvey


Alan W. Harvey (aharvey at
Assistant Curator of Invertebrates
American Museum of Natural History
Central Park West at 79th Street
New York, NY 10024
(212) 769-5638

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