衡量收入与收入不平等

中文摘要

收入不平等很重要，但衡量它的各种尝试却得出了截然不同的结论。为什么会这样？我们借助近期围绕美国收入不平等测度的争议，回归到关于收入概念与不平等测度这两方面的基本原理。我们强调两大要点。第一，没有任何一种收入分配衡量指标是真正全面的；若试图做到全面，就必然要作出有争议的选择。我们记录了标准理想概念——全面的Haig-Simons收入——所引发的实践与概念问题。第二，该领域的许多争议都取决于以个人税务数据为起点与采用更宽泛收入概念之间的诸多权衡。个人税务数据仅反映了更全面收入概念中一个不断缩小的子集——但它们是个体层面的数据。另一方面，更宽泛的替代方案则更难分配到个人。我们记录了这种分配所需的一些最重要且最具争议的假设。

Abstract

Income inequality is important, but attempts to measure it arrive at strikingly different conclusions. Why? We use recent disputes over measuring United States income inequality to return to first principles about both the income concept and inequality measurement. We emphasize two broad points. First, no measure of the income distribution is truly comprehensive, or could attempt to be comprehensive without making controversial choices. We document the practical and conceptual problems that the standard ideal — comprehensive Haig-Simons income — raises. Second, much of the controversy in this area turns on the many tradeoffs between starting with individual tax data versus more expansive income concepts. Individual tax data reflect only a shrinking subset of a more comprehensive income concept — but they are individual data. More expansive alternatives, on the other hand, are harder to allocate to individuals. We document some of the most important and contestable assumptions that such an allocation requires.