We study the percentage of welfare losses (PWL) yielded by imperfect competition under product differentiation. When demand is linear, even if prices, outputs, costs and the number of firms can be observed, PWL is arbitrary in both Cournot and Bertrand equilibria. If in addition the elasticity...

In this paper we study a two period contest where the strength of players in the second period depends on the result of the contest in the first stage. We show that in contrast to one-shot contests in the same setting, heterogeneous players exert different efforts in the first stage and rent...