Hello everyone, I use the following command lines to get important variable from training dataset. data.controls <- cforest_unbiased(ntree=500, mtry=3) data.cforest <- cforest(V1~.,data=rawinput,controls=data.controls) data.cforest.varimp <- varimp(data.cforest, conditional = TRUE) I got error: "Error in model.matrix.default(as.formula(f),data = blocks): term 1 would require 4e+17 columns" I changed data dimension to 150. The problem still exists. So, I guess there are other problems. Please give me some help or hints. Thanks! jinrui,