An uncertainty-averse agent prefers betting on an event whose probability is known, to betting on an event whose probability is unknown. Such an agent may randomize his choices to eliminate the effects of uncertainty. For what sort of preferences does a randomization eliminate the effects of uncertainty? To answer this question, we investigate an agent's preferences over sets of acts. We axiomatize a utility function, through which we can identify the agent's subjective belief that a randomization eliminates the effects of uncertainty.

This paper axiomatizes a utility function for social preferences under risk. In the model, a single parameter captures a preference for equality of opportunity (i.e., equality of exante expected payoffs) relative to equality of outcome (i.e., equality of ex-post payoffs). In a deterministic environment, the model reduces to the model of Fehr and Schmidt (1999). The model is consistent with recent experiments on probabilistic dictator games.

Halevy (2008) states the equivalence between diminishing impatience (i.e., quasi–hyperbolic discounting) and the common ratio effect. The present paper shows that one way of the equivalence is false and shows the correct and general relationships: diminishing impatience is equivalent to the certainty effect and that strong diminishing impatience (i.e., hyperbolic discounting) is equivalent to the common ratio effect. JEL: D81

The random utility model (RUM), a cornerstone in economics, is typically studied under the assumption that choice frequencies of all alternatives are observable. In practice, however, some alternatives have unobservable choice frequencies and are commonly aggregated into a single category called an outside option. We study RUM in such environments and derive a finite, nonredundant system of inequality constraints on observed choice frequencies that characterizes RU-rationalizability. We show that the conventional practice of aggregating unobserved alternatives can miss key information leading to incorrect conclusions such as that observed choices are rationalizable, even when no RUM is consistent with them.