Talk:Species diversity

Proportional Abundance?
"The true diversity in a dataset is calculated by first taking the weighted generalized mean Mq−1 of the proportional abundances of the types in the dataset, and then taking the reciprocal of this. "

Can you define proportional abundances? Is this a raw count of one type of species, or the number of one species divided by the universe of individuals?

Lead-in
The lead-in seems contradictory. "Species diversity is the number of different species that are represented in a given community (a dataset). [...] Species diversity consists of two components: species richness and species evenness. The first sentence provides no indication of the dependence of evenness whatsoever, and should be amended. —DIV (120.17.156.117 (talk) 05:20, 21 April 2017 (UTC))

Issues with some of the equation descriptions?
Working through some of the equations for specific values of q it seems like there might be some issues with this page. More specifically:

a) q = 0

The text states:

"q = 0 corresponds to the weighted harmonic mean, which is 1/S because the pi values cancel out." However, substituting zero for q yields a sum from 1 to S of 1, or just S, and so corresponds to the total number of species in the data set.

b) q = 2

The associated text states that this "corresponds to the arithmetic mean." But substituting 2 for 'q' actually yields the inverse Simpson's index

These results are also summarized on p.429 of one of the references cited for this page:

[https://www.researchgate.net/publication/201998256_Diversity_and_Evenness_A_Unifying_Notation_and_Its_Consequences Hill, M. O. (1973) Diversity and evenness: a unifying notation and its consequences. Ecology, 54, 427–432]

Perhaps these descriptions are meant to refer to just the denominator of the first form of the diversity equation, and not the diversity itself? If so, it would be helpful to clarify this in the associated text. Since I'm not one of the authors for the page, I wasn't sure of the etiquette for making (or requesting) changes like this.

Hjshapiro (talk) 01:37, 8 November 2017 (UTC)