[R-sig-eco] adonis() and collinearity

2014-09-17 Thread Jonas Kuppler 

Dear all,

if I use only continuous explanatory variables in the adonis() function 
it is like a multiple linear regression with dissimilarities.


In multiple regression with highly correlated exp. variables I have the 
problem with multicollinearity and an increasing standard error of the 
coefficents. Is it the same for the adonis() function? I would think so 
since adonis() is analogous to a MANOVA, but I am not sure. And is 
there any possibility to estimate the influence of multicollinearity in 
adonis(); like the variance inflation factor for lm?


Thanks  Best,

Jonas

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Re: [R-sig-eco] adonis() and collinearity

2014-09-17 Thread Jari Oksanen 
Dear Jonas Kuppler,

On 17/09/2014, at 16:06 PM, Jonas Kuppler wrote:

 
 if I use only continuous explanatory variables in the adonis() function it is 
 like a multiple linear regression with dissimilarities.
 
 In multiple regression with highly correlated exp. variables I have the 
 problem with multicollinearity and an increasing standard error of the 
 coefficents. Is it the same for the adonis() function?

Yes, it is.

 I would think so since adonis() is analogous to a MANOVA, but I am not 
 sure. And is there any possibility to estimate the influence of 
 multicollinearity in adonis(); like the variance inflation factor for lm?
 
Not directly: adonis does not return all intermediate results that are useful 
to find the vif. It could be modified to return those items and then it would 
be very simple to calculate vif. Not yet, though (neither in plans). There are 
some tricks that may work even with the current code: check Legendre  Legendre 
latest edition.

Cheers, Jari Oksanen
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