Doğan, B.Doğan, SerhatYıldız, Kemal2019-02-072019-02-0720180022-0531http://hdl.handle.net/11693/48988We introduce and analyze an efficiency criterion for probabilistic assignment of objects, when only ordinal preference information is available. This efficiency criterion is based on the following domination relation: a probabilistic assignment dominates another assignment if it is ex-ante efficient for a strictly larger set of utility profiles consistent with the ordinal preferences. We provide a simple characterization of this domination relation. We revisit an extensively studied assignment mechanism, the Probabilistic Serial mechanism (Bogomolnaia and Moulin, 2001), which always chooses a “fair” assignment. We show that the Probabilistic Serial assignment may be dominated by another fair assignment. We provide conditions under which the serial assignment is undominated among fair assignments.EnglishEx-ante efficiencyProbabilistic assignmentFairnessProbabilistic serial mechanismArticle10.1016/j.jet.2018.01.0111095-7235