On the Decomposition by Subgroups of the Gini's Index and Zenga's Uniformity and Inequality Indexes

Besides a brief historical outline of the Gini's index decomposition proposals, we compare, in a subgroups framework, the decompositions of the Gini index and of the uniformity index recently proposed by Zenga. The two decompositions follow a similar scheme and allow the within and between terms to be naturally obtained without an a priori definition and preserving the structure of the indexes itself.