FW: Czekanowski's coefficient - which is which.
buz at MAIL.USYD.EDU.AU
Mon Jun 1 06:17:29 CDT 1998
At 11:25 29/02/00 +1100, you wrote:
>From: Eddy Cannella [SMTP:cannella at ozemail.com.au]
>Sent: Thursday, May 28, 1998 5:04 PM
>To: ESA at dwe.csiro.au
>Subject: Czekanowski's coefficient - which is which.
>One particular coefficient is Czekanowski's coefficient of similarity.
>From my reading, this particular index is used when quantitative
(abundance) data is
>This formula is the same as that for Sorensons index on similarity.
>Would anyone out ther know whether this is an error or if the index was
>developed for both types of data (or is it an error on my part).
Your answer is in the documents to Eugene Gallagher's COMPAH96, available
at http://www.es.umb.edu/edgwebp.htm . He has a section on equivalencies
of indices. Here is an excerpt from the introduction to this section:
"Ecologists often use different names to describe the same index. For
example, Czekanowski's binary, Sorensen's index, and the Dice index are
synonyms (Clifford & Stephenson 1975, p. 55). Sometimes, ecologists call
different similarity indices by the same name. For example, COMPAH's %
similarity (SIMOPT=9) is not the same as Pielou's (1984) percentage
similarity (SIMOPT=6). Pielou's percentage similarity is known by several
synonyms: Czekanowski's quantitative index, Sorensen's quantitative index
(Magurran 1988, p. 95), and COMPAH's Bray-Curtis similarity index
(SIMOPT=6). " [Table follows]
This section on indices is the one of the most informative treatments that
I have come across. Gallagher goes on to develop other new indices. I post
this to the list in case others don't know about this useful software and
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