Sorry for the previous email. Problem solved! Stefano -- Stefano Calza, PhD Sezione di Statistica Medica e Biometria Dip. di Scienze Biomediche e Biotecnologie Universit? degli Studi di Brescia - Italia Viale Europa, 11 25123 Brescia email: calza at med.unibs.it Telefono/Phone: +390303717532 Fax: +390303717488 Section of Medical Statistics and Biometry Dept. Biomedical Sciences and Biotechnology University of Brescia - Italy