Mean-dispersion preferences and constant absolute uncertainty aversion

We axiomatize, in an Anscombe-Aumann framework, the class of preferences that admit a representation of the form V (f) = (d), where is the mean utility of the act f with respect to a given probability, d is the vector of state-by-state utility deviations from the mean, and (d) is a measure of (aversion to) dispersion that corresponds to an uncertainty premium. The key feature of these mean-dispersion preferences is that they exhibit constant absolute uncertainty aversion. This class includes many wellknown models of preferences from the literature on ambiguity. We show what properties of the dispersion function ( ) correspond to known models, to probabilistic sophistication, and to some new notions of uncertainty aversion.