[R-sig-ME] Question about proportion data in binomial glmm

[Thierry Onkelinx]

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 using inbo.be
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www.inbo.be

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Op vr 24 mrt 2023 om 02:39 schreef rtfiner <rtfiner using 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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