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This window displays the index calculated separately for each chosen sample.


This surprisingly simple index was considered by May (1975) to be one of the best.


It is simple measure of the numerical importance of the most abundant species.


d = Nmax / N


where Nmax is the number of individuals in the most abundant species, and N is the total number of individuals in the sample.


The reciprocal of the index, 1/d, is often used, so that an increase in the value of the index accompanies an increase in diversity and a reduction in dominance. We plot the dominance index d.


A simple plot of the way the index changes between samples is displayed by clicking on the Graph tab on the output window.


To compare two indices see Testing for significant differences between indices.