Affiliation: | 1. Department of Statistics, Federal University of Paraíba, Cidade Universitária, s/n, Postal Code 58051-900, Jo?o Pessoa (PB), Brazileufrasio@de.ufpb.br;3. Department of Statistics, Federal University of Paraíba, Cidade Universitária, s/n, Postal Code 58051-900, Jo?o Pessoa (PB), Brazil |