A measure used by ecologists when a system contains too many individuals for each to be identified and examined. A small sample is used; the index (D) is the ratio of the number of species to their importance values (e.g. biomass or productivity) within a trophic level or community.D=−Σpsi log pi, where s is the total number of species in the sample, i is the total number of individuals in one species, pi (a decimal fraction) is the number of individuals of one species in relation to the number of individuals in the population, and the log is to base-2 or base-e.
D=−Σpsi log pi
http://www.tiem.utk.edu/∼mbeals/shannonDI.html Explanation of the Shannon–Wiener index of diversity.
Subjects: Biological Sciences — Environmental Science.