Decreasing Impatience: A Criterion for Non‐stationary Time Preference and “Hyperbolic” Discounting
提出递减不耐烦（DI）作为衡量时间偏好非平稳性的标准，证明双曲或准双曲函数形式的关键属性是贴现函数对数的Pratt-Arrow凸性，并指出DI越大，在两阶段决策中越容易选择被支配选项，导致低效决策。
Abstract Despite recent interest in hyperbolic discounting, there has been little discussion of exactly what property of time preferences is instantiated by hyperbolic or quasi‐hyperbolic functional forms. The paper revives an earlier proposal in Prelec (1989) that the key property is Pratt–Arrow convexity of the log of the discount function, which corresponds to decreasing impatience (DI) at the level of preferences. DI provides a natural criterion for assessing the severity of departure from stationarity in that greater DI is equivalent to more choices of dominated options in two‐stage decision problems, as well as greater convexity of the log of the discount function. Inefficient choices may arise as intentional precommitments, or as unintended reversals of preference by “naïve” agents.