[R] Problem specifying Gamma distribution in lme4/glmer

Dieter Menne dieter.menne at menne-biomed.de
Sun Mar 21 17:00:17 CET 2010



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)?
> 
> 

Interesting idea. Do you know of a example where this was done (independent
of lmer)? We have similar data, were people are either symptom free (50%
with score 0), and the rest is smoothly distributed.

Dieter


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