[R-sig-eco] NMDS axes scores

[Martin Weiser]

Hi Conny,

AFAIK NMDS is *non-metric* and represents distances among objects, not
gradients along axes (known or unknown): distances along axes are
stretched as needed locally (NMDS works with rank order), even order of
the elements along axes does not tell anything. NMDS is great if you
want to say: Object A resembles object C more than it resembles object
B, even though C and B are quite similar.
Try this: run NMDS several times, aim for different number of axes (e.g.
1,2,3,5,10) and note the scores of the objects along the first one.  You
*may* get the same thing.

If you need scores of the objects in the ordination, use something with
well defined metrics and axes, e.g. PCA, CA.
 
HTH,
Martin

On 9.1.2016 05:41, Conny wrote:
> Hi all,
>
>  
>
> it has been frequently pointed out in this group, that NMDS axes scores
> shouldn't be used individually for further analysis.  
>
> I therefore would like to include both of my NMDS site scores as a response
> into a GLM model simultaneously.  Unfortunately, I couldn't find any advice
> on how to actually do this. I found a  couple of papers using NMDS scores in
> GLMs, but they all seem to use them individually, fitting separate models to
> each of the ordination axes.
>
>  
>
> I'm a bit at a loss here and any advice is very much appreciated,
>
> Conny
>
>
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>
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