ABSTRACT The Gini index is the most commonly used measure of income inequality. Like any single summary measure of a set of data, it cannot capture all aspects that are of interest to researchers. One of its widely reported flaws is that it is supposed to be overly sensitive to changes in the middle of the distribution. By studying the effect of small transfers between households or an additional increment in income going to one member of the population on the value of the index, this claim is re-examined. It turns out that the difference in the rank order of donor and recipient is usually the most important factor determining the change in the Gini index due to the transfer, which implies that transfers from an upper income household to a low income household receive more weight that transfers involving the middle. Transfers between two middle-income households do affect a higher fraction of the population than other transfers but those transfers do not receive an excessive weight relative to other transfers because the difference in the ranks of donor and recipient is smaller than the corresponding difference in other transfers. Thus, progressive transfers between two households in the middle of the distribution changes the Gini index less than a transfer of the same amount from an upper income household to a lower income household. Similarly, the effect on the Gini index when a household in either tail of the distribution receives an additional increment is larger than when a middle-income household receives it. Contrary to much of the literature, these results indicate that the Gini index is not overly sensitive to changes in the middle of the distribution. Indeed, it is more sensitive to changes in the lower and upper parts of the distribution than in the middle.

中文翻译：

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基尼不平等指数是否对收入分配中间的变化过于敏感？

摘要基尼系数是最常用的收入不平等衡量标准。像对数据集的任何单个汇总度量一样，它无法捕获研究人员感兴趣的所有方面。它被广泛报道的缺陷之一是，它应该对分发中间的变化过于敏感。通过研究家庭之间的小额转移或使一个人口中的一部分增加收入对指数价值的影响，对这一说法进行了重新审查。事实证明，由于转移，捐赠者和接受者的等级顺序差异通常是决定基尼系数变化的最重要因素，这意味着从高收入家庭向低收入家庭的转移所获得的权重更大。涉及中间的转移。两个中等收入家庭之间的转移确实比其他转移对人口的影响更大，但是相对于其他转移而言，这些转移的权重并不高，因为捐助者和接受者等级的差异小于其他转移的相应差异。 。因此，在分配中间的两个家庭之间的渐进转移对基尼系数的改变小于从高收入家庭向低收入家庭转移相同数额的基尼系数。同样，当分布两端的一个家庭获得额外增加时，其对基尼指数的影响要大于中等收入家庭获得该基尼指数时的影响。与许多文献相反，这些结果表明，基尼指数对分布中间的变化并不过于敏感。确实，它对分布的上部和下部的变化比中部更敏感。