[R] What error distribution should I use?

[Ben Bolker]

Lívia Dorneles Audino <livia.audino <at> gmail.com> writes:

> 
> I'm trying to make a glmm to identify the relationship between insect
> species richness with fragment size, isolation and time (different years).
> I already tried to analyse it using poisson distribution error, but I
> always face with the following warning:
> *glm.fit: fitted probabilities numerically 0 or 1 occurred *
> 
> This is probably hapenning because my dataset has a lot of zeros. So, what
> error distribution should I use?
> 

  I know you haven't gotten a lot of help on r-sig-mixed-models (sorry),
but it would probably be better to post this question there.  The answer
is that this is a warning, not an error, so it indicates a need for
caution but not necessarily that anything is wrong.  In this case,
an internal call to glm.fit() has difficulty when it tries to fit
a subset of that data that are all-zero or all-one.  It's quite possibly
OK, provided that you've looked at your results, plotted predicted values,
etc., and everything seems to make sense.