Dera all, a simple question on rpart: when I run rpart on some data sets, I do not always get the surrogate splits at the root node. This does not depend on the presence of missing data because none of my data sets contains any, nevertheless sometimes i get them sometimes no, I wonder why! Can anybody help me? thanks a lot, melina Carmela Cappelli Department of Statistics School of Political Science University of Naples Federico II Via RodinĂ² n. 22 80138 Naples, Italy tel: +39-081-2537553 fax:+39-081-2537466 [[alternative HTML version deleted]]