Inequality Among World Citizens: 1820–1992
研究了过去两个世纪全球居民福祉的分布，发现收入不平等在19世纪初至二战期间加剧，之后趋于稳定或增长放缓；早期不平等主要源于国内差异，后期则源于国家间差异。寿命不平等在19世纪加剧，但在20世纪下半叶逆转，可能缓解了收入不平等未改善的影响。
This paper investigates the distribution of well being among world citizens during the last two centuries. The estimates show that inequality of world distribution of income worsened from the beginning of the 19th century to World War II and after that seems to have stabilized or to have grown more slowly. In the early 19th century most inequality was due to differences within countries; later, it was due to differences between countries. Inequality in longevity, also increased during the 19th century, but then was reversed in the second half of the 20th century, perhaps mitigating the failure of income inequality to improve in the last decades.