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Is there a workaround for non-convergence in glmmTMB models using the dredge function of MuMin?

I've tried to use the dredge-function of the MuMin-Package for a negative binomial generalized linear mixed model fitted with the package glmmTMB.

Because my full-model failed to converge, I've tried the workaround as described here: Dredge with the global model failing to converge

But when I use a simplified model and rewrite the function in model$call$function, dredge ignores this change and uses the simplified model instead of the full model.

Is there maybe another workaround for functions of the glmmTMB-package?

Below some example code:

# The full_model does not converge
full_model <- glmmTMB(y ~ x1 * x2 * (x3 + x4 + x5 + x6) + (1|RE1/RE1.1/RE1.2) + (1|RE2), data = df, family = "nbinom2")

# The simple_model does converge
simple_model <- glmmTMB(y ~ x1 + x2 + x3 + x4 + x5 + x6 + (1|RE1/RE1.1/RE1.2) + (1|RE2), data = df, family = "nbinom2")

# Change formula in the model
simple_model$call$formula <- y ~ x1 * x2 * (x3 + x4 + x5 + x6) + (1|RE1/RE1.1/RE1.2) + (1|RE2)

# use dredge, but this ignores the changed formula
dredge(simple_model)

Thank you!

Solution

  • You would have to replace the elements of simple_model $ modelInfo $ allForm. These are three formulas: "formula", "ziformula", and "dispformula", but in the case of your model only the first one is used.