On Fri, 2009-07-17 at 18:27 -0400, Evan Weiher wrote:
> If you use the diversity function in R, youll probably have to fix the
> cases where richness = 0 because it returns H = 0 for zero species:
>
> richness = specnumber(ex1)
> H = diversity(ex1)
> eff.rich = exp(H)
>
> for (i in 1:length(rich
Maria --
If you're getting sample counts so low as zero, you might well question
whether the they are reasonable estimators for the population
proportions the Shannon-Wiener index depends on. As a practical matter,
your resulting variances may be too high to enable you to distinguish
among tr
Hi everyone,
I think Lou Josts numbers equivalents should help solve this. He
suggested that the Shannon diversity index is very helpful, but it needs to
be translated back to the effective number of species (=e^H, assuming youve
calculated it using the natural log).
This way, you can inte
zero.
It sounds to me like UA or US (which is it?) may have too many philosophers
on staff!
Bill Silvert
- Original Message -
From: "Eric Lamb"
To:
Sent: Friday, July 17, 2009 12:14 PM
Subject: Re: [ECOLOG-L] Shannon-Wiener Div Index Question - dealing with
zero specie
iety of America: grants, jobs, news
[ecolo...@listserv.umd.edu] On Behalf Of Bill Silvert [cien...@silvert.org]
Sent: Friday, July 17, 2009 7:43 AM
To: ECOLOG-L@LISTSERV.UMD.EDU
Subject: Re: [ECOLOG-L] Shannon-Wiener Div Index Question - dealing with zero
species per plot??
After reading this pos
The consensus seems to be that diversity should be zero, but we should
consider the larger question before the mechanics of calculating a
particular index.
I recently had to deal with a similar question: what is the evenness of a
community with zero species?. The consensus among those I discussed
x fits into the analysis.
Bill Silvert
- Original Message -
From: "Maria Van Dyke"
To:
Sent: Thursday, July 16, 2009 6:39 PM
Subject: [ECOLOG-L] Shannon-Wiener Div Index Question - dealing with zero
species per plot??
I have a question about utility of the Shannon-Wiener d
> 718-982-3869
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718-982-3852
>
>
> -Original Message-
>
From: Ecological Society of America: grants, jobs, news
> [mailto:ecolo...@listserv.umd.edu] On Behalf Of Maria Van Dyke
> Sent: Thursday, July 16, 2009 5:39 PM
> To:
ECOLOG-L@LISTSERV.UMD.EDU
> Subject: [
, 2009 5:39 PM
To: ECOLOG-L@LISTSERV.UMD.EDU
Subject: [ECOLOG-L] Shannon-Wiener Div Index Question - dealing with zero
species per plot??
Dear ECO loggers,
I have a question about utility of the Shannon-Wiener diversity index in
regards to sampling units that have no species in them at a given sampling
America: grants, jobs, news
[ecolo...@listserv.umd.edu] On Behalf Of Maria Van Dyke [mt...@virginia.edu]
Sent: Thursday, July 16, 2009 2:39 PM
To: ECOLOG-L@LISTSERV.UMD.EDU
Subject: [ECOLOG-L] Shannon-Wiener Div Index Question - dealing with zero
species per plot??
Dear ECO loggers,
I have a
Dear ECO loggers,
I have a question about utility of the Shannon-Wiener diversity index in
regards to sampling units that have no species in them at a given sampling
time. Normally this would get a value of zero, however with Shannon-Wiener a
sampling unit that has only one individual of one specie
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