Measuring relative equality of concentration between different income/wealth distributions

In a recent paper Burrell (2005a) introduced two new measures both based on the Gini mean difference for measuring the similarity of concentration of productivity between different informetric distributions. The first was derived from Dagum’s (1987) notion of relative economic affluence (REA); the second – in some ways analogous to the correlation coefficient – is a new approach giving the so-called co-concentration coefficient (C-CC). Models and methods adopted in the field of informetrics – very roughly, the “metrics” aspects of “information systems” are very often based upon, or have direct analogues with, or at very least are inspired by, ones from econometrics and it is the purpose of this paper to suggest ways in which these new measures of similarity could be useful in, for instance, studies of income distributions (a) between different countries and (b) over different periods of time. The measures are illustrated using exponential, Pareto, Weibull and Singh-Maddala distributions.