[R-sig-ME] GLMM hurdle model for continuous data -Truncated negative binomial family in glmmTMB?

[Alessandra Bielli]

Dear List

I have posted the question below on Cross Validated as well, where you can
find the image of the diagnostics plots.
https://stats.stackexchange.com/questions/481109/truncated-negative-binomial-hurdle-model-for-continuous-data-glmmtmb



I am running a hurdle model using the glmmTMB function. My dependent
variable is continuous and >= 0. I was looking for a function that would
allow me to model the binary response in a logistic regression (i.e the
zero inflated model) and the non-zero response in a Gamma (log) regression
(i.e the conditional model). However, the glmmTMB function does not allow
to use the gamma family.

I have two questions:

   1.

   is there a function that allows to run a GLMM with gamma family? I tried
   to write my own code to have these two models but I am not sure about how
   to predict and calculate CIs.
   2.

   Is it appropriate to use a truncated negative binomial family for the
   conditional (non-zero values) model? I ran the model:

hpm_nb <- glmmTMB(percapita_dia ~ Tipo_residuo + (1|Trip_ID),
zi=~Tipo_residuo, all, family=truncated_nbinom2)

The diagnostics plots look good and model predictions are reasonable. Is it
still wrong to have a truncated negative binomial family?

Thanks for your help,

Alessandra

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