In this paper, we combine two alternative procedures for decomposing the Gini index: the Silber matrix approach and the Dagum technique based on Gini mean difference. This combined decomposition can be used for overlapping as well as no overlapping population subgroups. The presented decomposition procedure derives the within-group, the between-group, and the overlapping inequalities by exploiting all of the information on income distribution contained in one matrix accounting for pair wise disparities between per capita income shares. Moreover, this matrix approach can serve the scope of counting the frequency of overlapping, providing new insights for a more complete analysis of overlapping. The suggested methodology is applied to survey data on Italian employee incomes in 2000 and 2008.
Inequality measure; Gini decomposition; overlapping.
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