On Wed, 8 Nov 2006, Baoqiang Cao wrote: > Dear All, > > I am using wilcox.test to test two samples, data_a and data_b, earch sample > has 3 replicates, suppose data_a and data_b are 20*3 matrix. Then I used the > following to test the null hypothesis (they are from same distribution.): > > wilcox.test(x=data_a, y=data_b, alternative="g") > I got pvalue = 1.90806170863311e-09. > > When I switched data_a and data_b by doing the following: > wilcox.test(x=data_b, y=data_a, alternative="g") > I got pvalue = 0.999999998111886. > > I suppose because I am test them with same null hypothesis,
no, you don't: H_0: mean(data_a) <= mean(data_b) (alternative = "greater") is different from H_0: mean(data_b) <= mean(data_a) check wilcox.test(x=data_a, y=data_b, alternative="l") Torsten > I should get same result (pvalue). Since I am not a savy statistician at > all, maybe that is a wrong assumption, could anyone please point out the > right interpretion please? > > Thanks! > > Best, > Baoqiang > > ______________________________________________ > [email protected] 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. > > ______________________________________________ [email protected] 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.
