[R-sig-eco] calculate "dispersion index" (betadisper, vegan)

[Natalie]

hi zoltan
do you have another idea to calculate the dispersion?
thanks

Am 30.07.2015 07:52 schrieb Zoltan Botta-Dukat:
> Hi Natalie,
> 
> Be careful with convex hull volume, because it is zero if points lie
> on a line (an near to zero, if the configuration is close to this),
> independently from the amount of distances.
> 
> Zoltan
> 
> 2015.07.29. 19:26 keltezéssel, Natalie írta:
>> hi all
>> 
>> I would like to  calculate a dispersion index or similar from the 
>> results of the vegan function betadisper.
>> i would like to know if there is a possibility to e.g. calculate the 
>> volume of the community dispersion(area of the hull in the PCoA) from 
>> the betadisper results.
>> common is to show the distance to the centroid.but I have the 
>> impression the dispersion within communities are not that 
>> clear,especially if you have similar variance.
>> The program primer v5 calculates a disperion index based on  the 
>> similarity percentage.
>> similarity percentage is not an option since it is mainly based on 
>> most counted species.
>> 
>> ideas and help are very much appreciated
>> cheers natalie
>> 
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> 
> 
> --
> Botta-Dukát Zoltán
> --------------------------------
> Ökológiai és Botanikai Intézet
> Magyar Tudományos Akadémia
> Ökológiai Kutatóközpont
> --------------------------------
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> 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
> 
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