[R-sig-eco] EstimateR and Chao 1 standard deviation

["José M. Blanco Moreno"]

Hello again,

Thanks Bob for your prompt response to my silly question. Apart from
ignoring your work, I was overlooking that the variance expression
computed by estimateR is the "classic" expression in appendix B on
EstimateS web page, while I was trying to compute the bias-corrected one.

That takes me to the discrepancy that I was actually detecting: as
currently reported, S.chao1  refers to the unbiased estimator, while
se.chao1 refers to the biased estimator (I refer to the names and
formulae used on the EstimateS web page) except for the small sample
corrections.

Shouldn't these match?

Sincerely acknowledging the efforts to keep this wonderful tool that is
vegan (and its pieces),

José M.


El 17/10/2014 15:17, r-sig-ecology-request at r-project.org escribió:
> Unless Jari added something, the functions come from my paper from about
> 10 years ago:
> O?Hara RB (2005) Species richness estimators: how many species can dance
> on the head of a pin? J Anim Ecol 74: 375?386.
> http://doi.wiley.com/10.1111/j.1365-2656.2005.00940.x, which refers to
> Chao (1987), which is cited in the estimateR documentation. EstimateS
> now uses a small sample correction:
> <http://viceroy.eeb.uconn.edu/EstimateS/EstimateSPages/EstSUsersGuide/EstimateSUsersGuide.htm#Chao1AndChao2>
> Does this account for the discrepancy?
>
> Bob

--
---------------------------------------
José M. Blanco-Moreno
Dept. de Biologia Vegetal (Botànica)
Facultat de Biologia
Universitat de Barcelona
Av. Diagonal 643
08028 Barcelona
SPAIN
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phone: (+34) 934 039 871
fax: (+34) 934 112 842
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