FW: Czekanowski's coefficient - which is which.
Jeremy J. Bruhl
jbruhl at METZ.UNE.EDU.AU
Tue Feb 29 11:25:52 CST 2000
-----Original Message-----
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.
Hi to everyone,
I am reviewing a number of similarity/disimilarity (distance) =
coefficients often used in ecological data analysis. One problem I have =
come across is the numerous names under which some coefficients are =
known.
One particular coefficient is Czekanowski's coefficient of similarity. =
>From my reading, this particular index is used when quantitative =
(abundance) data is available and has the formula:
S(c)=3D[2(sum(min(Xj,Yj)}]/(sum Xj + sum Yj)
Yet, I have also come across another formula for this index which is =
used
with binary data (presence/absence). The formula is
S(c)*/(2a + b + c)=20
(see Clifford H.T. and Stephenson W. 1975 " An introduction to numerical =
classification". Academic Press. Pp55)
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).
Any help would be appreciated.
Thank you in advance
Eddy Cannella
cannella at ozemail.com.au
More information about the Taxacom
mailing list