Opportunism and the Dynamics of Incomplete Contracts
研究买卖关系中质量不可合同化但受努力和卖方私人信息影响的情况，发现两份以上合同多余，合同序列价格和期限递增，承诺未来价格会引发机会主义而非努力。
This paper studies a buyer-seller relationship where "quality" is not \n contractible but is affected by effort and the seller's privately known innate \n value. The seller's cost of effort is also private knowledge. Assuming constant \n outside opportunities, we show that more than two contracts is redundant, the \n sequence of contracts exhibits increasing prices and durations, and commit- \n ments for prices beyond the actual contract invite opportunism, not effort. The \n seller uses effort during the screening process, which improves noncontract- \n ible quality. As a result, type-related information may have negative value \n when contracts are incomplete.