I'm investigating associations between socioeconomic factors and dichotomous outcome. I use generalised linear models (GLM) with log link for Bernoulli family, i.e., modelling the prevalence ratio. At the epidemiology course of K.J. Rothman & E.Hatch we were told, that goodness of fit tests are designed to prediction models and in causal inference it is not important with model fit. I can not find any reference on that. Can anybody comment on this and suggest a reference? Thank you in advance!