Index of dispersion - Wikipedia
https://en.wikipedia.org/wiki/Index_of_dispersionThe first to discuss the use of a test to detect deviations from a Poisson or binomial distribution appears to have been Lexis in 1877. One of the tests he developed was the Lexis ratio. This index was first used in botany by Clapham in 1936. If the variates are Poisson distributed then the index of dispersion is distributed as a χ statistic with n - 1 degrees of freedom when n is large and is μ > 3. For many cases of interest this appro…
Index of dispersion - Wikipedia
en.wikipedia.org › wiki › Index_of_dispersionin probability theory and statistics, the index of dispersion, dispersion index, coefficient of dispersion, relative variance, or variance-to-mean ratio (vmr), like the coefficient of variation, is a normalized measure of the dispersion of a probability distribution: it is a measure used to quantify whether a set of observed occurrences are …