In statistics, deviance is a goodness-of-fit statistic for a statistical model; it is often used for statistical hypothesis testing. It is a generalization of the idea of using the sum of squares of residuals in ordinary least squares to cases where model-fitting is achieved by maximum likelihood.

How do you calculate deviance?

More precisely, the deviance is defined as the difference of likelihoods between the fitted model and the saturated model: D=−2loglik(^β)+2loglik(saturated model).

What does the deviance represent?

Deviance refers to behaviors that violate social norms.