Quantile-Quantile Plot for Negative Binomial Distribution I am performing regression analysis in R on count data which are negative binomial distributed. I would like to use a quantile-quantile plot as a tool to diagnose the fit of my models, but I am struggling to find an appropriate method for my data. A Normal Q-Q plot would not be appropriate since the residuals are not expected to be Normally distributed, so I think I need to compare my residuals against theoretical quantiles from the negative binomial distribution. I have tried using the 'qqPlot' function from the 'car' package, but I can't seem to get it to work properly.

The package performance has this and other features for negative binomial regressions.
https://easystats.github.io/performance/
By using check_model() with the model, you will have several outputs that may help you understand the performance of your model.
Also, recently discovered DHARMa package, which uses a simulation-based approach to produce residuals plots. It works with complexed models (hierarchichal or mixed models) but, can also lead with negative-binomial ones. Take a look: https://cran.r-project.org/web/packages/DHARMa/vignettes/DHARMa.html
