Inequality and the tails

Working Paper 2015-366


This paper revisits the earlier assessments of the Palma Proposition and the ‘Palma Ratio’. The former is a proposition that currently changes in income or consumption inequality are (almost) exclusively due to changes in the share of the richest 10 per cent and poorest 40 per cent because the ‘middle’ group between the richest and poorest always capture approximately 50 per cent of gross national income (GNI). The latter is a measure of income or consumption concentration based on the above-mentioned proposition and calculated as the GNI capture of the richest 10 per cent divided by that of the poorest 40 per cent. In this paper we do the following: note the use already being made of the Palma Ratio; consider the issue of hidden (or partially hidden) inequality and how the Palma may be useful in bringing this to light in the parts of the distribution that we are likely to be more interested in (the richest and the poorest); revisit the empirical basis of the Palma Proposition (the relative stability of the ‘middle’) with a new and expanded dataset across and within developing and developed countries. We find the data reaffirms the Palma Proposition and that the proposition is getting stronger over time. We also discuss the theoretical and empirical questions and implications arising from the Palma Proposition as areas for future exploration.

Authors: Alex Cobham, Luke Schlogl, Andy Sumner.