Cournot Platform Competition with Mixed-Homing

This paper proposes a sufficient statistics approach to welfare analysis of third-degree price discrimination in differentiated oligopoly. Specifically, our sufficient conditions for price discrimination to increase or decrease aggregate output, social welfare, and con-sumer surplus simply entail a cross-market comparison of multiplications of two or three of the sufficient statistics—pass-through, conduct, and profit margin—that are functions of first-order and second-order elasticities of the firm’s demand. Notably, these results are derived under a general class of demand, and can be readily be extended to accom-modate heterogeneous firms. These features suggest that our approach has potential for conducting welfare analysis without a full specification of an oligopoly model.