multiple regression (ONKELINX, Thierry)

Dear Alain,

Thank you for your comments.

Interesting thought. Maybe correct. But there are a few 
things to think
about:
1. You have to assume that sampling was such that all species 
out there have ended up in the data. Formulated 
differently...you need to know the N_i (maximum number of 
possible species) in the B(p_i,N_i).

I assume that one knowns all species that could occur in the region.
That is not the same as all samples species.

2. Not sure how the variance structure would work out; 
Poisson or NB versus Binomial. I guess it may work out ok.
3.  B(p_i,N_i) means N_i independent (!) trials, each (!) 
with probability p_i of success. But what happens if these 
trials (=species) are not independent?

Agreed that this might be problematic. But isn't this also a problem
with a Poisson model? Since you assume that the number of species only
depends on the covariantes and not on the presence of some species?

Anyway....it is not my problem....but you would need to think 
about these things.

I was replying to a question. So it is is my problem neither ;-) Or are
least not at present, as I might get similar datasets in the future.

Alain

Best regards,

Thierry

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