Coefficient of Community

CC = \frac{c}{s_{1} + s_{2} - c}

$"CC" = "c" /( s_1 + s_2 - "c" )$

$(c)"Number of species in common to both communities"$

$(s_1)"Number of species in community 1."$

$(s_2)"Number of species in community 2."$

The Math / Science

The '''Jaccard index'''¹, also known as '''Intersection over Union''' and the '''Jaccard similarity coefficient''' (originally coined ''coefficient de communauté'' by Paul Jaccard), is a statistic used for comparing the Similarity measure and diversity index of sample sets. The Jaccard coefficient measures similarity between finite sample sets, and is defined as the size of the intersection divided by the size of the union of the sample sets:

$J(A,B) = {{|A \cap B|}/{|A \cup B|}} = {{|A \cap B|}/{|A| + |B| - |A \cap B|}}.$

(If ''A'' and ''B'' are both empty, we define J(A,B) = 1.)

0 ≤ J(A,B) ≤ 1

The Coefficient of Community (Jaccard Coefficient) is a coefficient that indicates the degree of similarity of two communities based on the number of species that they have in common. The formula for the Coefficient of Community is:

$"CC" = c/(S_1+S_2-c)$

where:

CC is the Jaccard Coefficient of Community
S₁ is the number of species in community 1
S₂ is the number of species in community 2
c is the number of species in common between community 1 and community 2

Community Statistics Calculators

Reference

^ The description of Jaccard index is from Wikipedia: en.wikipedia.org/wiki/Jaccard_index