[1] Univ Florence, Dept Stat Comp Sci Applicat G Parenti, Viale Morgagni 59, I-50134 Florence, Italy
[2] Renmin Univ China, Sch Stat, Beijing 100872, Peoples R China
[3] Univ Castilla La Mancha, Fac Social Sci Cuenca, Cuenca Campus,Camino Pozuelo s-n, Cuenca 16071, Spain