Question about proportion data in binomial glmm

Dear Robert,

IMHO you should remove the cbind(0, 0) before fitting the model. There is
no reason to keep them in the dataset.

Best regards,

ir. Thierry Onkelinx
Statisticus / Statistician

Vlaamse Overheid / Government of Flanders
INSTITUUT VOOR NATUUR- EN BOSONDERZOEK / RESEARCH INSTITUTE FOR NATURE AND
FOREST
Team Biometrie & Kwaliteitszorg / Team Biometrics & Quality Assurance
thierry.onkelinx at inbo.be
Havenlaan 88 bus 73, 1000 Brussel
www.inbo.be

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Op vr 24 mrt 2023 om 02:39 schreef rtfiner <rtfiner at gmail.com>:

I have a question about how glmmtmb handles proportion data for the
purposes of a binomial glmm.

I combined my success and failure count data into a matrix using cbind(),
and used that as my response in my binomial glmm using glmmtmb.

However, despite there being a few instances of zero counts in both columns
and therefore an undefined proportion, the model doesn't seem to drop these
rows from my data set.

I don't get any errors or warnings when running the model, but I worry my
results might be biased because of this.

My question is: Is glmmtmb doing something like adding a tiny amount to
each value of my response in order to avoid dealing with undefined
proportion data?

Thank you for your help,

Robert

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