Note sur quelques méthodes d’évaluation de l’inégalité dans la répartition des revenus par groupe, basées sur l’indice Gini

In this paper, we compare three methods presently used to split up the Gini index in order to evaluate the contribution of one particular factor (for example, age) to the value of this index: the B-M-P decomposition*, Paglin's measures and Love & Wolfson indexes. The problem with the decomposition of the Gini index is that it is impossible to cut it in two parts, one, representing the value of inequality attributable to the factor analysed and the second, inequality due to other factors. We also have to include the value of overlaps. This is clearly shown by Bhattacharya and Mahalanobis.