In This Paper, We Generalize Hoy and Robson (1981) Analysis and We Provide a Necessary and Sufficient Condition for Insurance Not to Be Giffen. the Condition Gives a Bound for the Variation of the Absolute Risk Avesion Which Pemits the Wealth Effect to Be Always Dominated by the Subsitution Effect.

At any given point in time, the collection of assets existing in the economy is observable. Each asset is a function of a set of contingencies. The union taken over all assets of these contingencies is what we call the set of publicly known states. An innovation is a set of states that are not...