I thinnk the answer is much simpler. The print method for hypothesis tests (class htest) truncates the p-values. In the above example, instead of using
wilcox.test(rnorm(100), rnorm(100, 2), exact=TRUE) and copying the output, just print the p-value: tst = wilcox.test(rnorm(100), rnorm(100, 2), exact=TRUE) tst$p.value [1] 2.988368e-32 I think this value is what the journal asks for. HTH, Peter On Thu, Mar 18, 2021 at 10:05 PM Spencer Graves <spencer.gra...@effectivedefense.org> wrote: > > I would push back on that from two perspectives: > > > 1. I would study exactly what the journal said very > carefully. If they mandated "wilcox.test", that function has an > argument called "exact". If that's what they are asking, then using > that argument gives the exact p-value, e.g.: > > > > wilcox.test(rnorm(100), rnorm(100, 2), exact=TRUE) > > Wilcoxon rank sum exact test > > data: rnorm(100) and rnorm(100, 2) > W = 691, p-value < 2.2e-16 > > > 2. If that's NOT what they are asking, then I'm not > convinced what they are asking makes sense: There is is no such thing > as an "exact p value" except to the extent that certain assumptions > hold, and all models are wrong (but some are useful), as George Box > famously said years ago.[1] Truth only exists in mathematics, and > that's because it's a fiction to start with ;-) > > > Hope this helps. > Spencer Graves > > > [1] > https://en.wikipedia.org/wiki/All_models_are_wrong > > > On 2021-3-18 11:12 PM, Bogdan Tanasa wrote: > > <https://meta.stackexchange.com/questions/362285/about-a-p-value-2-2e-16> > > Dear all, > > > > i would appreciate having your advice on the following please : > > > > in R, the wilcox.test() provides "a p-value < 2.2e-16", when we compare > > sets of 1000 genes expression (in the genomics field). > > > > however, the journal asks us to provide the exact p value ... > > > > would it be legitimate to write : "p-value = 0" ? thanks a lot, > > > > -- bogdan > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > > 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. > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
