I am working with observational data which has a right skew in the dependent variable. This is a mixed effect model with a poisson distribution as based on discrete data. After finding the residuals from the model were not normal, and sjstats function overfit(model) highlighted zero-inflation to be an issue I ran the model in glmmTMB:
fit_zipoisson <- glmmTMB(freq~(B1 + B2)+(1|ref),data=da, ziformula=~1, family=poisson())
But running the model diagnostics afterwards still reveal a non-normal distribution and a zero-inflation.
zero_count(fit_zipoisson) Zero-Count overfitting Observed zero-counts: 295 Predicted zero-counts: 100 Ratio: 0.34 Model is underfitting zero-counts (probable zero-inflation). Shapiro-Wilk normality test data: resid(fit_zipoisson) W = 0.57262, p-value < 2.2e-16
Does anyone have any advice on what to do next?