A decomposição do índice de Hirschman-Herfindahl

Abstract

Firstly, a relation between the coeficient of variation and the Hirschman-Herfindahl index of concentration of an industry is deduced. Then, assuming that the firms in the industry are distributed in K groups, it is shown that the Hirschman-Herfindahl index is a function of the concentration among groups and the concentration within groups. The Hirschman-Herfindahl indexes for concentration among groups and within groups are defined so that the decomposition of the measure of concentration of the whole industry is coherent with the corresponding decomposition of the population variance.