[R-sig-ME] Binomial glmer() with zero-inflated data
mollieebrooks at gmail.com
Fri Apr 13 13:50:37 CEST 2018
You probably don’t need to worry about zero-inflation. The binomial distribution should be able to handle the 0s. Your model seems reasonable to me.
Mollie E. Brooks, Ph.D.
National Institute of Aquatic Resources
Technical University of Denmark
> On 13Apr 2018, at 13:39, Jessie Barker <jessiebarker at gmail.com> wrote:
> Dear mixed-model enthusiasts,
> I have a question about how to model zero-inflated data (I have several 1's
> too, but more 0's).
> The data are observations of bees visiting flowers to collect nectar. A
> visit can either be "pollination" or "nectar robbing" (the bee collects
> nectar from a hole through the side of the flower). Each bee made a
> sequence of visits, and the response variable that I am interested in is
> how many times a bee robbed nectar. (In many cases a bee did not rob nectar
> at all - hence the zero-inflation - and in a few cases it only robbed
> nectar.) I observed each bee only once.
> The predictor variable I am interested in is the proportion of flowers on
> the plant that have holes in them (thus enabling nectar robbing). I have
> multiple measurements of the response variable on each plant, but only one
> measurement of the predictor variable. So I will include plant as a random
> I think I need something like this:
> model1 <- glmer ( cbind(rob,pollinate) ~ prop.holes + (1|plant),
> data=mydata, family=binomial)
> But I don't think that can handle the zero-inflation. Does anyone on this
> listserv have any advice?
> Thanks in advance - I really appreciate any suggestions!
> Best wishes,
> Jessie Barker
> Junior Fellow
> Aarhus Institute of Advanced Studies, Denmark
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