We study the matching of workers to firms in which workers choose an observable and contractable effort after the match. If there are complementarities between a worker’s ability and a firm’s technology, positive assortative matching (PAM) is the only matching in any equilibrium and is the unique efficient matching. We investigate the effect of a policy that changes the matching of firms to workers from any matching to PAM, such as implementing a centralized clearing house. We characterize two sets of sufficient conditions on the production and cost functions under which the total output and welfare both increase. Under the first set of conditions, the increase in total output is an upper bound for the efficiency gain. In contrast, under the second set of conditions, the increase in total output is a lower bound for the efficiency gain. We identify a third set of conditions under which the total output decreases while welfare increases.

我们研究了工人与公司的匹配，其中工人在匹配后选择可观察和可收缩的努力。如果工人的能力和企业的技术之间存在互补性，那么正选配匹配（PAM）是任何均衡中唯一的匹配，也是唯一的有效匹配。我们研究了将公司与工人的匹配从任何匹配改为 PAM 的政策的效果，例如实施集中清算所。我们描述了生产和成本函数的两组充分条件，在这些条件下，总产出和福利都增加。在第一组条件下，总产出的增加是效率增益的上限。相反，在第二组条件下，总产出的增加是效率增益的下限。我们确定了第三组条件，在这些条件下总产出下降而福利增加。