# Null and Residual deviance [duplicate]

I am running a glm family = poisson for count data.

I am not really sure how to interpret my null and residual deviance and haven't found anything else useful to help explain how to actually interpret and what the values mean (aka if my model is an ok fit):

(Dispersion parameter for poisson family taken to be 1)

Null deviance: 3429.4  on 4438  degrees of freedom
Residual deviance: 1694.6  on 4430  degrees of freedom
AIC: 19511


I have done 1 - (residual / null) and got a value of 0.5058611

Does this mean that my R^2 is 0.5? If not, what do these values mean and how to I use them to look at the fit of my model?

Thanks!

• I think you will find the information you need in the linked thread. Please read it. If it isn't what you want / you still have a question afterwards, come back here & edit your question to state what you learned & what you still need to know. Then we can provide the information you need without just duplicating material elsewhere that already didn't help you. – gung - Reinstate Monica Aug 1 at 18:40