Dear R-experts I recently tried out the Salford Systems MARS software on a large dataset. Apparently MARS outperformed traditional techniques such as logistic regression and k-nearest-neighbor. Since I usually perform all my data analyses in R I have installed the 'mda' package but I seem to get much worse results with R than with the Salford Systems software. In my data set I have 7 continuous predictors and a binary outcome. The training data set has 100.000 samples. I try to use the same parameters I used in the MARS program: mars(x=train.set,y=response,degree=2,nk=80,penalty=3) With the MARS program I would get GCV values of approximately 0.11 but with R I get 0.15. The corresponding reduction in area under the operator characteristics curve (AUC) is from 0.83 to 0.70. What am I doing wrong? Thanks in advance! Kim Mouridsen.