On Dagum’s Decomposition of the Gini Coefficient

To measure the contributions to inequality from population subgroups, the Gini coefficient is often decomposed into inequality within groups, inequality between groups and a residual term arising from the overlapping of income distributions from different groups. In this paper we show that two decompositions presented separately in the literature, a traditional decomposition and a decomposition suggested by Dagum (1997), are identical, a fact not previously acknowledged in the literature