Some Further Results on Random Obic Rules

Abstract

We study the structure of probablisitic voting rules that are ordinal Bayesian incentive compatible (OBIC) with respect to independently distributed prior beliefs that can be considered generic (Majumdar and Sen, 2004). We first identify a class of priors, such that for each prior in that class there exists a probabilistic voting rule that puts a positive probability weight on ``compromise'' candidates. The class of priors include generic priors. Next, we consider a class of randomized voting rules that have a ``finite range". For this class of rules, we identify an appropriate generic condition on priors such that, any rule in this class is OBIC with respect to a prior satisfying the generic condition if and only if the rule is a random dictatorship.

Keywords: ordinal Bayesian incentive compatibility, generic priors, random dictatorship.