Optimal Retention in Agency Problems
研究一个长期委托人与一系列短期代理人之间的互动，同时存在道德风险和逆向选择。委托人只能通过留用规则影响代理人行为，且规则须序贯理性。文章给出了均衡存在的条件，并分析了代理人生产率随时间下降但平均高于未试用者的现象。
This paper studies the interaction between a single long-lived principal and a series of short-lived agents in the presence of both moral hazard and adverse selection. We assume that the principal can influence the agents' behavior only through her choice of a retention rule; this rule is further required to be sequentially rational (i.e., no precommitment is allowed). We provide general conditions under which equilibria exist where (a) the principal adopts a “cut-off” rule under which agents are retained only when the reward they generate exceeds a critical bound; and (b) agents separate according to type, with better agents taking superior actions. We show that in equilibrium, a retained agent's productivity is necessarily declining over time, but that retained agents are also more productive on average than untried agents due to selection effects. Finally, we show that for each given type, agents of that type are more productive in the presence of adverse selection than when there is pure moral hazard (i.e., when that type is the sole type of agent in the model); nonetheless, adding uncertainty about agent-types cannot benefit the principal except in uninteresting cases.