[1] Univ Valencia, Dept Estadist & Invest Operat, Avda Dr Moliner 50, Burjassot 46100, Spain
[2] Univ Valencia, Dept Matemat Econ & Empresa, Avda Tarongers S-N, Valencia 46022, Spain
[3] Univ Politecn Valencia, Dept Matemat Aplicada, Camino Vera S-N, Valencia 46022, Spain