Good day all, My first posting to this list. It looked like the best place to post this question.
When running the wilcox.test(), I noticed that the output values change if you change the ordering of the levels (example below which includes a t.test for comparison). I think this has something to do with the change in ranking order, but this doesn't make much sense as I would expect the ranking in this case to remain constant as there are no ties. So my questions are: a) is this correct (i.e. not a bug)?, and b) if it is, then which values should I report? x <- cbind(data.frame((c(rep("A",50),rep("B",50)))),runif(100)) colnames(x) <- c("a","b") wilcox.test(b~a,data=x) t.test(b~a,data=x) x$a <- relevel(x$a,ref="B") wilcox.test(b~a,data=x) t.test(b~a,data=x) Thank you in advance for your time, Regards, Alastair [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.