Discrete Choice and Rational Inattention: a General Equivalence Result

This paper establishes a general equivalence between discrete choice and rational inattention models. Matejka and McKay (2015, AER) showed that when information costs are modelled using the Shannon entropy, the resulting choice probabilities in the rational inattention model take the multinomial logit form. We show that when information costs are modelled using a class of generalized entropies, then the choice probabilities in any rational inattention model are observationally equivalent to some additive random utility discrete choice model and vice versa. This equivalence arises from convex- analytic properties of the random utility model. Thus any additive random utility model can be given an interpretation in terms of boundedly rational behavior. We provide examples of this equivalence utilizing the nested logit model, an empirically relevant random utility model allowing for flexible substitution possibilities between choices.