order 2: The Gibbs–Martin index of sociology, psychology, and management studies, which is also known as the Blau index, is the same measure as the Gini–Simpson index. The quantity is also known as the expected heterozygosity in population genetics. Berger–Parker index The Berger–Parker index equals the maximum value in the dataset, i.e., the proportional abundance of the most abundant type. This corresponds to the weighted generalized mean of the values when approaches infinity, and hence equals the inverse of the true diversity of order infinity (). See also References Further reading See chapter 5 for an elaboration of coding procedures described informally above. External links Simpson's Diversity index Diversity indices gives some examples of estimates of Simpson's index for real ecosystems. Measurement of biodiversity Index numbers Summary statistics for categorical data