1. Health Research Centre, Department of Nursing, Physiotherapy and Medicine, University of Almería, Carretera del Sacramento s/n, La Cañada de San Urbano, 04120 Almería, Spain
2. Random Models and Design of Experiments, Department of Mathematics, University of Almería, Carretera del Sacramento s/n, La Cañada de San Urbano, 04120 Almería, Spain