How innocuous is it to approximate globally decreasing impatience with quasi-hyperbolic discounting?
研究了用准双曲贴现模型近似全局递减不耐烦的消费者行为时，模型能否准确预测均衡策略和比较静态，并指出其在评估抑制过度消费措施时存在偏差，尤其高估了有效性和福利影响。
This paper studies the behavior of a consumer whose time preferences exhibit globally decreasing impatience. We ask how well this behavior could be approximated with quasi-hyperbolic discounting. We find that a quasi-hyperbolic approximation can reproduce the consumer’s equilibrium strategies and their local comparative statics. However, such an approximation would provide biased assessments of measures to mitigate excessive consumption. We identify a range of biases relating to investment in illiquid assets, and to corrective taxes on sin goods. The quantitative implications of these biases are evaluated in numerical examples. For plausible parameter values, the quasi-hyperbolic approximation significantly overstates the effectiveness and the welfare consequences of the responses to excessive consumption.