Dear Christoph,

don't know if anybody has responded (only obtain the digests).

For identification of relevant descriptors, you could run the RDA with forward entering of variables as in multiple regression.
A nice introduction can be found in Borcard D., Gillet F. & Legendre P. (2011) Numerical ecology with R, Springer, New York, NY.
pages 154 following

There is also a statistical test for the number of axes implemented in R - see:
Legendre P., Oksanen J. & Ter Braak C.J.F. (2011) Testing the significance of canonical axes in redundancy analysis. Methods in Ecology and Evolution, 2, 269-277.


HTH
Ralf

Am 01.08.2014 um 12:00 schrieb r-sig-ecology-request@r-project.org:

> Send R-sig-ecology mailing list submissions to
> 	r-sig-ecology@r-project.org
> 
> To subscribe or unsubscribe via the World Wide Web, visit
> 	https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
> or, via email, send a message with subject or body 'help' to
> 	r-sig-ecology-request@r-project.org
> 
> You can reach the person managing the list at
> 	r-sig-ecology-owner@r-project.org
> 
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of R-sig-ecology digest..."
> 
> 
> Today's Topics:
> 
>   1. equilibrium circle in RDA ordination?
>      (Christoph Eberhard Freiherr von Redwitz)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Thu, 31 Jul 2014 12:29:13 +0000
> From: Christoph Eberhard Freiherr von Redwitz
> 	<christoph.redwitz@uni-rostock.de>
> To: "r-sig-ecology@r-project.org" <r-sig-ecology@r-project.org>
> Subject: [R-sig-eco] equilibrium circle in RDA ordination?
> Message-ID:
> 	<CD3BA13216175B4190B57B8CC02C42040107AEDE41@mbx3.uni-rostock.de>
> Content-Type: text/plain
> 
> Hi!
> I am running a (tb-)RDA with Hellinger transformed (species) abundance data. To interpret the response I use some criteria:
> The axes which are worth to look at: broken stick method
> The axes I want to look at: explained variance
> 
> Now comes the question: is there a criterion to decide which descriptors/species are worth to interpret? In PCA I would use the equilibrium circle. Can I use it in RDA?
> 
> Best wishes
> Christoph
> 
> 	[[alternative HTML version deleted]]
> 
> 
> 
> ------------------------------
> 
> _______________________________________________
> R-sig-ecology mailing list
> R-sig-ecology@r-project.org
> https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
> 
> 
> End of R-sig-ecology Digest, Vol 77, Issue 1
> ********************************************


	[[alternative HTML version deleted]]

