On Mar 21, 2010, at 5:16 PM, Ben Bolker wrote:
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.
I thought this was what hurdle and ZIF models were supposed to handle
gracefully?
--
David.
Ben Bolker
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