Can anyone help me to compute manually de CP cost-parameter in library rpart when the command printcp is executed in a Classification tree?? Thank you very much Alberto Cebollada Solanas Grupo de Gen?tica de Micobacterias (http://genmico.unizar.es/) CIBERes - CIBER Enfermedades Respiratorias (http://www.ciberes.org) Facultad de Medicina - Aulario A Universidad de Zaragoza C/ Domingo Miral s/n CP 50009-Zaragoza, Arag?n alberto at unizar.es Tel: +34-976-762420 Fax: +34-976-762420