I have been analyzing count data using Poisson distribution in glmmTMB, and just ran some DHARMA diagnostics. However, there don't seem to be a lot of help online on how to interpret the results. Does the left graph indicate underdispersion? And if the red line is all the way to the right - is it overdispersion?

And does the right graph show that there is no zero inflation? When running zero_count(model1) from sjstats, the result indicates that the model is overfitting zero counts - meaning no zero inflation?

Dispersion and zero inflation tests


1 Answer 1


The left hand plot shows your actual dispersion with a histogram of simulated residuals. Since your value is to the left it indicates that your model has under-dispersion. The right hand plot shows the simulated number of zeroes with your actual number shown as red. You have fewer zeroes than expected.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.