1. B3, Praça Antônio Prado 48 01010‐901 São Paulo SP Brazil
2. Department of StatisticsUniversity of Campinas Rua Sérgio Buarque de Holanda 651 13083‐859 Campinas SP Brazil
3. University of Campinas Rua Sérgio Buarque de Holanda 651 13083‐859 Campinas SP Brazil