Fixing Our Public Discounting Systems
本文指出西方国家使用单一贴现率评估公共投资和政策，忽略了风险成本差异，导致资本错配和福利损失。基于资产定价文献，提出应根据项目净收益的收入弹性调整贴现率，以识别保险收益，改革福利收益大且方法简单。
Most Western countries use a single discount rate to evaluate public investments and policies. This ignores the differential cost of risk, in a world where most risk markets exhibit surprisingly large prices of risk. The current discounting guidelines generate a misallocation of capital that entails a large welfare cost. We claim that the well-established asset pricing literature provides a strong normative justification in favor of risk-adjusting discount rates. More specifically, project-specific discount rates should be increasing in the income elasticity of the project's net benefit. This will favor projects whose net benefit materializes preferentially in low-income states, thereby recognizing their insurance benefit ex ante. The intuition is simple, the welfare benefit of the reform is large, and the methodology only requires evaluators to estimate an income elasticity on top of what is required in the current approach. It is time to fix our public discounting systems.