TABLE 1. Names, formulas and alternate names for included similarity coefficients. Variables in the formulae are: a = number of shared species, b = number of species found only in the first sample, and c = the number of species found only in the second sample.

 

Coefficient Name

Formulae

Alternate Name

Function Call

 

Jaccard

a/(a+b+c)

Coefficient of Community

jaccard()

 

Sorenson

2a/(2a+b+c)

Dice, Czekanowski, Coincidence Index

sorenson()

 

Simpson

a/(a+min(b,c))

-

simpson()

 

Braun-Blanquet

a/(a+max(b,c))

-

braun.blanquet()

 

Ochiai

a/sqrt{(a+b)(a+c)}

Coefficient of Closeness

ochiai()

 

Kulczynski

[a/(a+b)+a/(a+c)]/2

-

kulczynski()