PS. Mayby I can somehow try to transform data and check it, for example, using the skewness-function of timeDate-package?
> Thanks. What I have had to ask is that > > how do you test that the data is symmetric enough? > If it is not, is it ok to use some data transformation? > > when it is said: > > "The Wilcoxon signed rank test does not assume that the data are > sampled from a Gaussian distribution. However it does assume that the > data are distributed symmetrically around the median. If the > distribution is asymmetrical, the P value will not tell you much about > whether the median is different than the hypothetical value." > > > On Wed, Jun 23, 2010 at 10:27 PM, Atte Tenkanen <atte...@utu.fi> wrote: > > > Hi all, > > > > > > I have a distribution, and take a sample of it. Then I compare > that > > sample with the mean of the population like here in "Wilcoxon signed > > > rank test with continuity correction": > > > > > >> wilcox.test(Sample,mu=mean(All), alt="two.sided") > > > > > > Wilcoxon signed rank test with continuity correction > > > > > > data: AlphaNoteOnsetDists > > > V = 63855, p-value = 0.0002093 > > > alternative hypothesis: true location is not equal to 0.4115136 > > > > > >> wilcox.test(Sample,mu=mean(All), alt = "greater") > > > > > > Wilcoxon signed rank test with continuity correction > > > > > > data: AlphaNoteOnsetDists > > > V = 63855, p-value = 0.0001047 > > > alternative hypothesis: true location is greater than 0.4115136 > > > > > > What assumptions are needed for the population? > > > > wikipedia says: > > "The Wilcoxon signed-rank test is a _non-parametric_ statistical > > hypothesis test for... " > > it also talks about the assumptions. > > > > > What can we say according these results? > > > p-value for the "less" is 0.999. > > > > That the p-value for less and greater seem to sum up to one, and that > > the p-value of greater is half of that for two-sided. You shouldn't > > ask what we can say. You should ask yourself "What was the question > > and is this test giving me an answer on that question?" > > > > Cheers > > Joris > > > > -- > > Joris Meys > > Statistical consultant > > > > Ghent University > > Faculty of Bioscience Engineering > > Department of Applied mathematics, biometrics and process control > > > > tel : +32 9 264 59 87 > > joris.m...@ugent.be > > ------------------------------- > > Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php ______________________________________________ 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.
