Choice deferral and ambiguity aversion

When confronted with uncertain prospects, people often exhibit both choice deferral and Ellsberg-type ambiguity aversion. This paper obtains a joint representation for these behavioral phenomena. The decision maker as portrayed by my model is willing to choose an uncertain prospect f over g rather than to defer this choice if and only if the expected utility of f is greater that or equal to the expected utility of g for every probability measure in a convex and closed set ∆. This set is interpreted as a collection of the decision maker’s possible future beliefs. When choices cannot be deferred, the decision maker evaluates every uncertain prospect via an "-mixture of the least favorable element in the set ∆ and her current probabilistic belief p ∈ ∆. All components of my model are derived from observable preferences in an essentially unique way. K. Choice deferral, ambiguity aversion, epsilon contamination, multiple priors model, subjective probability, Ellsberg paradox. JEL . D81, D83.