[R] Problem specifying Gamma distribution in lme4/glmer

Ben Bolker bolker at ufl.edu
Sun Mar 21 22:16:32 CET 2010


Dieter Menne <dieter.menne <at> menne-biomed.de> writes:
 
> Ben Bolker wrote:

> >  3. zero-inflated data may not be particularly well-represented
> > by a Gamma distribution: if you actually have a significant number
> > of exactly-zero values, you may want to analyze your data in two
> > stages, first as a presence-absence problem and then as a conditional
> > density (i.e., what is the distribution of the non-zero values)?

> [...] Do you know of a example where this was done (independent
> of lmer)?  [...]

  Nothing springs to mind, but it seems sensible.

  Ben Bolker



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