Hi everybody, I'm working with the affy packages lately and one aspect I would like to evaluate for myself is the agreement between the results returned by the standard affymetrix GCOS software and the corresponding values delivered by the BioC-MAS-functions. Until now I can perform the calculation of the expression values and the call values by the one sided wilcoxons signed rank test. But I can't find any function calculating the two sided rank test indicating whether there has been an increase, decrease or no change in expression between two probes or probe groups. Has anybody an idea whether such a function is already implemented in the packages? regards, benjamin