手法を比較

	Palma Ratio	Atkinson Index
分野	Sociology	Sociology
系統	Process / pipeline	Process / pipeline
提唱年	2011 (Palma's finding); 2013–2014 (the ratio)	1970
提唱者	Gabriel Palma; named by Cobham & Sumner	Anthony Barnes Atkinson
種類	Tail-ratio inequality measure	Welfare-based, parameterized inequality index
原典	Cobham, A., & Sumner, A. (2014). Is inequality all about the tails? The Palma measure of income inequality. Significance, 11(1), 10–13.	Atkinson, A. B. (1970). On the measurement of inequality. Journal of Economic Theory, 2(3), 244–263.
別名	Palma index, Palma measure, top10/bottom40 ratio	Atkinson inequality measure, Atkinson's A, welfare-based inequality index
関連	5	5
概要	The Palma ratio measures income inequality as the ratio of the income share held by the richest 10 percent of the population to the share held by the poorest 40 percent. It rests on the empirical regularity, documented by Gabriel Palma, that the middle deciles (5 through 9) capture a remarkably stable half of national income across countries, so that inequality is essentially a contest between the top and the bottom — the 'tails' of the distribution.	The Atkinson index is a welfare-based measure of inequality that incorporates an explicit, analyst-chosen parameter for how much society dislikes inequality. Introduced by Anthony Atkinson in 1970, it asks what fraction of total income could be discarded, under an equal distribution, while leaving social welfare unchanged — making the ethical judgement behind any inequality comparison transparent rather than hidden.