Re: AFCVI

From: Stephane DRAY (dray@biomserv.univ-lyon1.fr)
Date: Wed Nov 12 2003 - 22:21:31 MET


At 10:03 11/11/2003, Sara Mouro wrote:
>Could anyone please tell me how can I plot the AFCVI results, related to a
>typical X1 = (SitesxSpp matrix) and a X2 = (SitesxEnvironmental variables)
>analysis?
>
>I already know how to interpretate the inertia decomposition results but
>it is not easy to show and explain the others those numbers. So I would
>prefer to graphycally display those results...
>
>Should I use the Scatters module? and with which file extensions (--.ivta,
>--.ivvp, --.ivco, --.ivfa...)?
>
>Hope someone have the time to send me some help on this. Please!!
>
>Regards
>Sara Mouro.

Dear Sara,
two interpretations and so two graphical possibilities are available for
AFCVI (see http://pbil.univ-lyon1.fr/R/articles/arti112.pdf).
  You can see it at the end of the report file of your analysis:
|----------------------------------------------
| files mycca.ivc1
| mycca.ivls
| mycca.ivli
| allow a convenient interpretation
|----------------------------------------------
| files mycca.ivfa
| mycca.ivl1
| mycca.ivco
| allow a convenient interpretation
|----------------------------------------------

The second one (fa - l1 - co):
CCA looks for weights (fa) to obtain linear combination of environmental
variables of unit norm (l1) maximizing the separation of species niche
centroid (co). This is the most usual interpretation of CCA (ter Braak 's
point of view)

Use scatter module on these files (label and arrow).



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