[R-sig-eco] Rao entropy with presence-absence data

[Zoltan Botta-Dukat]

Dear Thomas,


>
> Is it possible, and meaningful, to calculate  Rao`s quadratic entropy 
> index (function dbFD from package FD) with presence-absence data?
Yes, it is possible and meaningful. In this case it is simply the mean 
distance between the occurring species.


> I don't get a error message but when I use the function with 
> (...,scale.Rao=TRUE) the calculations never end.
I think this problem is not related to p/a data. Calculation may demand 
long time for large datasets.
Anyway, I think scaling by the possible maximum is meaningless if you 
don't have abundance data.

Best wishes

Zoltan

>
> Thank you for your answer.
>
> /Thomas
>


-- 
Botta-Dukát Zoltán
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Ökológiai és Botanikai Intézet
Magyar Tudományos Akadémia
Ökológiai Kutatóközpont
--------------------------------
2163. Vácrátót, Alkotmány u. 2-4.
tel: +36 28 360122/157
fax: +36 28 360110
botta-dukat.zoltan at okologia.mta.hu
www.okologia.mta.hu


Zoltán BOTTA-Dukát
--------------------------------
Institute of Ecology and Botany
Hungarian Academy of Sciences
Centre for Ecological Research
--------------------------------
H-2163 Vácrátót, Alkomány u. 2-4.
HUNGARY
Phone: +36 28 360122/157
Fax..: +36 28 360110
botta-dukat.zoltan at okologia.mta.hu
www.okologia.mta.hu