Natural Resource BiometricsMeasures of DiversityFormated version of this page for printingSimpson's indexSimpson's index is the first of a set of nonparametric approaches to determining sample heterogeneity. Simpson (1949) did not want to make assumptions about the distribution of the species abundance curve and so defined the following: Simpson's indexwhere D is Simpson's index of similarity and can be defined as the probability of two individuals in a random sample being in same category. P_{i} is the proportion of category i in the community.
Peet (1974) suggested that Simpson's index is of a type that is more sensitive to the common categories in your sample. Simpson's index values should be interperted with this in mind. Also see: Chapter 10  Species Diversity Measures pages 357360 in:

Natural Resources Biometrics by David R. Larsen is licensed under a Creative Commons AttributionShareAlike 4.0 International License . Author: Dr. David R. Larsen Created: March 9, 2001 Last Updated: Nov 2, 2016 