[R-sig-eco] Building glmms to handle zero-inflated continuous data in R - what options are available? (especially relating to hurdle/mixture models)

[Gavin Simpson]

How complex are the random effects? I they are relatively simple, give the
mgcv package a look. Its gam() function can fit Tweedie models optimising
over the Tweedie parameter too, and you can include random effects via
splines using `bs = "re"`.

G

On 17 June 2015 at 15:57, Karan Odom <kjodom at gmail.com> wrote:

> Hi,
>
> I have a zero-inflated continuous data set and want to build a glmm in R to
> analyze it (I have both fixed and random effects). However, because my data
> are continuous, I am discovering that this is not a simple task.
> Zero-inflation options in glmmABMD are not appropriate because my data are
> continuous and I don't know what other packages exist that allow for
> zero-inflated glmms with continuous data.
>
> I tried implementing the Tweedie distribution using packages tweedie and
> cplm, but these are a poor fit to my data.
>
> I think hurdle or mixture models might be especially useful for my data.
> When I modeled the non-zero continuous data separately from the
> zero/non-zero data, I get a very good fit to the data. However, I am stuck
> at how to integrate the two models. There seem to be packages in R that do
> this for count data but I have not found them for continuous data.
>
> I have been reading previous r-sig-ecology posts about this and find a lot
> of information from 2008-2012. I was wondering in the last few years if
> there have been developments in and if there are now available: (1)
> packages or techniques for easily implementing glmms for zero-inflated data
> in R, and (2) are there any good packages for mixture or hurdle models in R
> that allow for continuous data (i.e., how can I integrate the two models
> for the zero/non-zero versus non-zero continuous data)?
>
> Thank you very much for any help!
> Karan
>
> --
> Karan J. Odom
> Ph.D. Candidate, Biological Sciences
> University of Maryland, Baltimore County
> 1000 Hilltop Circle
> Baltimore, MD 21250
>
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-- 
Gavin Simpson, PhD

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