[R] tweedie and lmer

[Ben Bolker]

Mohammad AlMarzouq <koutbo6 <at> gmail.com> writes:

> 
> Hello all,
> 
> I have count data with about 36% of observations being zeros. I found  
> in some of the examples of the r-help mail archives that a tweedie  
> family of distributions could be used to fit a model with random  
> effects. Upon installing the tweedie package and attempting to fit the  
> following model:
> 
> lmer(SUS ~ 1 + (1| 
> GRP),REML=FALSE,data=mydata,family=tweedie(var.power=1.55,link.power=0))
> 
> I get the following error:
> 
> Error in famType(glmFit$family) : unknown GLM family: ‘Tweedie’
> 
> If it helps, im on a mac with R V 2.9.1, lme4 V.0.999375-31, Tweedie  
> V2.0.
> 


  I'm surprised that you found evidence that tweedie could
be used with lmer: in general, lmer only allows families that
have been hard-coded (and doesn't allow families with "extra"
parameters, such as negative binomial, beta-binomial, tweedie
etc.).  Perhaps you were reading about lme?

  Ben Bolker