[R] Total inertia in package Vegan?

Gavin Simpson gavin.simpson at ucl.ac.uk
Wed Nov 24 13:49:54 CET 2010

On Wed, 2010-11-17 at 13:23 +0100, Hedberg Peter wrote:
> Dear all at the R-project help list.
> I have run into a problem when it comes to getting values for "total
> inertia" and "R-squared" for my DCA using "decorana" in the package
> "vegan". I have tried the "goodness" function, but the reply indicates
> that it does not work with "decorana" class objects. In Canoco one
> gets the Total inertia in the output together with 4 eigenvalues. In
> decorana one gets the 4 eigenvalues, but not the Total inertia.
> Is there a way for me to get the Total inertia without having to go
> over to Canoco?

OK, I might well be being incredibly stupid, but Total Inertia doesn't
change with CA/DCA. Just run cca() on your matrix and grab the inertia.
Whether you can compare the eigenvalues from decorana() and cca() I
can't quite remember. Jari should be able to tell you - drop us a line
on the Vegan R-Forge page:


I'll take this opportunity to question why you are using DCA at all?


> Best regards,
> Petter Hedberg
> ___________________________________
> NOCC, http://nocc.sourceforge.net

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