Evaluating the Gini's index for income group distribution: a proposal

When an income distribution is presented in grouped form without information regarding the classes mean income (or total), the problem concerning which hypothesis should be assumed with respect to the income distribution into each class arises. It is quite common to assume that all the class incomes equals the class mark. In this paper we propose an alternative approach and examine it effects, compared with the former, both with respect to the Lorenz curve and the Gini index. The proposal is finally interpreted into the subgroups framework.