[R-sig-eco] adonis and negative F-values

[v_coudrain at voila.fr]

Dear all,
I used adonis to perform a test of the pairwise site dissimilarity indices proposed by Baselga (2010, 2012) in the package betapart. I am concerned about my results 
because I get some negative F-values. I read in another post that this may happen because of the presence of negative eigenvalues. However I was wondering if 
this does invalidate the results, or if they are still interpretable in some way. Moreover in case the results are still valid, do you think that providing a result table 
containing negative F-values will be considered for publication or be an argument of refusal? I may use distance-based RDA with the cailliez correction instead, 
would it be a good alternative to adonis for testing the effect of a three-level factor on the dissimilarity measures?

Best wishes,
Valerie Coudrain
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