search for: deltafits

...) then fits a number of submodels, computing for each some measure DeltaFit of the relative change in goodness of fit. It then returns to stepAIC() with some indication of which submodel is best. addterm.glm behaves similarly. The problem is, both functions use the submodel deviances to compute the DeltaFits, not the submodel AICs, even though these are available for at least the poisson, binomial and negbin families. The step() function works much the same way. Is this behaviour correct? It is not obvious to me that the deviance-based criteria will produce the same sequence of steps as the AIC criter...