[R-sig-ME] glmmTMB: Including variable in as fixed effect and in dispersion model

[Andre Syvertsen]

Hi guys,

Is it possible/meaningful to include a variable both as a fixed effect and in the dispersion model? For example, I have run the following model:

m4DaysPlayed <- glmmTMB(daysPlayed ~ 1 + time + ageCategory * gender + (time | id), disp = ~time, dfLong, family = truncated_nbinom2)

Rationale: I want to study the effect of time on the outcome variable, but I have also found evidence for heteorskedasticity when simulating through DHARMa. I suspect that the time variable influences this, the sample size decreases/variation increases as time goes on.

Kind regards,
Andr�

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