[R] lmer{lme4}, poisson family and residuals

[Ben Bolker]

Amelie LESCROEL <lescroel_cebc <at> no-log.org> writes:

> 
> Hello,
> 
> I’m trying to fit the following model:
> 
> Dependent variable: MAXDEPTH (the maximum depth reached by a penguin during
> a given dive)
> 
> Fixed effects: SUCCESSMN (an index of the “individual quality” of a bird),
> STUDYDAY (the day of the study, from -5 to 20, with 0=Dec 20), and the
> interaction SUCCESSMN*STUDYDAY
> 
> Random effect: BIRD (the bird id, as each bird is performing several dives)
> 

  It isn't immediately clear to me why the maximum depth should
be Poisson-distributed ... as R is trying to tell you, Poisson
distributions only make sense for integer data.  Your best bets
are probably (1) reconsider the error distribution, (2) perhaps
trying using nlme instead of lmer -- it is more polished, and you
can use Pinheiro and Bates "Mixed-Effects Models in S and S-PLUS"
as a reference.

  Ben Bolker