On Tue, Oct 23, 2012 at 11:52 PM, Luigi <marongiu.luigi at gmail.com> wrote: > > Any tip on how to proceed? You may want to do check rocplus package. Its vignette is pretty good. http://cran.r-project.org/web/packages/rocplus/vignettes/rocplus.pdf In your case, I think pairwise comparison would be one approach Best, Mehmet