[R-sig-ME] poisson GLMER with identity link

[Tim Carnus]

Dear list,

I am trying to fit a number of GLMERs to count data with an additive
model (in the predictors) that requires the use of the identity link
function. For about half of my response variables this causes no
problems. However in a number of cases the model fitting runs into
problems with regards estimation of negative mean (for e.g. the error
message in mer_finalize: mu[i] must be positive: mu = 1.76267e-312, i =
13075456). As far as I understand this is well known and documented, and
guarding against that possibility is necessary, and built in to say the
glm() function.

My question then is, how can I do this with lmer? (ie how can I specify
the constraints necessary to fit these types of models, if at all
possible)

Best regards,

Tim Carnus