Universal service obligations in the postal sector: The relationship between quality and coverage

This paper examines competition in the postal sector when one private incumbent and one entrant play a three-stage game. First, firms choose their coverage. Then, they choose the quality of the mail. Finally, firms choose the price. I modify the traditional model of product differentiation proposed by Mussa and Rosen [Mussa, M., Rosen, S., 1978. Monopoly and product quality. Journal of Economic Theory 18, 301-317] in order to consider that firms decide their quality and coverage. Valletti et al. [Valletti, T., Hoernig, S., Barros, P., 2002. Universal service and entry: the role of uniform pricing and coverage constraints. Journal of Regulatory Economics 21 (2), 169-190] show that when an incumbent is regulated by a uniform pricing constraint the entrant will choose a low level of coverage to increase the incumbent's uniform price and weaken competition. In this paper, I show that by increasing product differentiation, the entrant can obtain the same price increase with a smaller reduction of coverage. Acknowledgement of the strategic link between quality and coverage can be very useful in the design of a regulatory policy. The paper also considers a mixed duopoly in which the public firm covers the entire market and offers high quality service. In this context, I explain that the mixed equilibrium implements the first-best qualities and coverage levels.