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 =
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 =
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

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