simpson {untb} | R Documentation |
Simpson's diversity index
simpson(x)
x |
Ecosystem vector; coerced to class count |
Returns the Simpson index D: the probability that two randomly sampled individuals belong to different species. This is
1-sum((p_i)^2)
where p_i is the relative frequency of the i-th species
Early versions of the untb package effectively defined D as the probability that two randomly selected different individuals belong to different species
Robin K. S. Hankin
10.1111/j.1461-0248.2005.00729.x
data(butterflies) D <- simpson(butterflies) theta <- optimal.prob(butterflies)*2*no.of.ind(butterflies) #compare theta with D/(1-D) (should be roughly equal): theta D/(1-D)