DRG prospective payment systems: refine or not refine?
研究了医保购买方对同一诊断下两种治疗方案（医疗与手术）是否应设定不同价格（细化）的问题，发现细化价格会导致医院过度提供手术，而不细化则可能因利他程度低而手术不足，最终表明价格细化未必最优。
We present a model of contracting between a purchaser of health services and a provider (a hospital). We assume that hospitals provide two alternative treatments for a given diagnosis: a less intensive one (for example, a medical treatment) and a more intensive one (a surgical treatment). We assume that prices are set equal to the average cost reported by the providers, as observed in many OECD countries (yardstick competition). The purchaser has two options: (1) to set one tariff based on the diagnosis only and (2) to differentiate the tariff between the surgical and the medical treatment (i.e. to refine the tariff). We show that when tariffs are refined, the provider has always an incentive to overprovide the surgical treatment. If the tariff is not refined, the hospital underprovides the surgical treatment (and overprovides the medical treatment) if the degree of altruism is sufficiently low compared with the opportunity cost of public funds. Our main result is that price refinement might not be optimal.