Re: NANFA-L-- Diversity Indicies

Irate Mormon (archimedes at
Thu, 29 Sep 2005 13:34:26 -0400

Quoting "Todd D. Crail" <tcrail at UTNet.UToledo.Edu>:
> So if I'm understanding what I'm reading about Hill's, it will account for
> the discrepantcy in the biomass? I'm just looking for a simple way to
> compare multiple yet similar sites within a watershed, using the fish
> community sampled as the response variable.


I have to reveal my ignorance and naivete here. My coursework was in classical
zoology - I never studied stuff like population modeling, diversity indices,
etc., although I do have a strong mathematical background. But if you're just
looking to pin a diversity number on a site, relative to the whole, why not
simply use a ratio of species collected? I.E. there are 100 species in the
river, you collect 20 at site X, so that's a diversity of .20 or something like
that. If you use an index that factors in the number of individuals of a
certain species collected, then that is going to skew your number, especially
with the relatively small samples you produced in your examples. I also don't
understand why you would want to weight one species more heavily than another,
if I understand that to be your intention?

I am hoping you can outline it for me without me having to read through a bunch
of papers which I probably don't have access to anyway. Perhaps we listizens
can create our own index which will serve your purpose.


Dogs need to sniff the ground; it's how they keep abreast of current events. The
ground is a giant dog newspaper, containing all kinds of late-breaking dog news
items, which, if they are especially urgent, are often continued in the next
yard. - Dave Barry
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