> From: Christoph Buser > > Hi > > "t.test" assumes that your data within each group has a normal > distribution. This is not the case in your example.
Eh? What happen to the CLT? Andy > I would recommend you a non parametric test like "wilcox.test" if > you want to compare the mean of two samples that are not normal > distributed. > see ?wilcox.test > > Be careful. Your example produces two gamma distributed samples > with rate = 10, not scale = 10. > rate = 1/scale. > If you want to use scale, you need to specify this argument > x<-rgamma(40, 2.5, scale = 10) > see ?rgamma > > I do not see the interpretation of your result. Since you do > know the distribution and the parameters of your sample, you > know the true means and that they are different. It is only a > question of the sample size and the power of your test, if this > difference is detected. > Is that something you are investigating? Maybe a power > calculation or something similar. > > Regards, > > Christoph Buser > > -------------------------------------------------------------- > Christoph Buser <[EMAIL PROTECTED]> > Seminar fuer Statistik, LEO C13 > ETH (Federal Inst. Technology) 8092 Zurich SWITZERLAND > phone: x-41-44-632-4673 fax: 632-1228 > http://stat.ethz.ch/~buser/ > -------------------------------------------------------------- > > [EMAIL PROTECTED] writes: > > Hi R Users > > I have a code which I am running for my thesis work. Just > want to make sure that > > its ok. Its a t test I am conducting between two gamma > distributions with > > different shape parameters. > > > > the code looks like: > > > > sink("a1.txt"); > > > > for (i in 1:1000) > > { > > x<-rgamma(40, 2.5, 10) # n = 40, shape = 2.5, Scale = 10 > > y<-rgamma(40, 2.8, 10) # n = 40, shape = 2.8, Scale = 10 > > z<-t.test(x, y) > > print(z) > > } > > > > > > I will appreciate it if someone could tell me if its alrite or not. > > > > thanks > > > > -dev > > > > ______________________________________________ > > R-help@stat.math.ethz.ch mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
