Randomization with Asymmetric Information

It is by now well-known that, in the presence of moral hazard or adverse selection, randomization of insurance premia and benefits may be Pareto efficient. This paper: i) provides a typology of the various forms that randomization may take; ii) derives necessary and/or sufficient conditions for the desirability of these various forms of randomization; iii) obtains some simple characterization theorems of the efficient random policies; iv) gives some intuition behind the results; and v) considers why randomization appears to occur less often in practice than the theory suggests it should.