Pielou J (Each Sample)

This measure of equitability compares the observed Shannon-Wiener index against the distribution of individuals between the observed species which would maximise diversity.

If H is the observed Shannon-Wiener index, the maximum value this could take is log(S), where S is the total number of species in the habitat. Therefore the index is:

J = H/log(S).

There is a big problem with this index. You do not know S! The program assumes that the total number of species, S, is the maximum observed in any one sample.