I would like to do recursive partitioning when the response is a count variable subject to overdispersion, using say negative binomial likelihood or something like quasipoisson in glm. Would appreciate any thoughts on how to go about this (theory/computation). If I understand the rpart documentation, I would need to write a method argument, but the details are not there. Therefore, a second question is whether/where one can get material on developing new rpart implementations. regards, Farrar [[alternative HTML version deleted]]