A crucial assumption in the optimal auction literature has been that each bidder's valuation is known to be drawn from a single unique distribution. In this paper we relax this assumption and study the optimal auction problem when there is ambiguity about the distribution from which these...

Shelling (1960) among others have argued that contributions to public goods may be larger if people spread their contributions and give one small contribution at a time. Examining a threshold public good environment, Marx and Matthews (2000) show that multiple rounds may secure a provision level...

Despite sustained efforts of equal opportunities for men and women, large gender differences prevail in competitive high ranking positions. Possible explanations include discrimination, differences in human capital and preferences, which overall may make women less effective in competitive...