# Re: [R] gamma distribution

Date: Thu 28 Jul 2005 - 05:24:43 EST

Hi
You are right but here I am taking into account the p values I get from the tests on the raw and the transformed samples. And then I calculate the power of the tests based on the # of rejections of the p values. DO you think its a good way to determine the power of a test?

thanks

-dev

Quoting Christoph Buser <buser@stat.math.ethz.ch>:

> Hi
>
> I am a little bit confused. You create two sample (from a gamma
> distribution) and you do a wilcoxon test with this two samples.
> Then you use the same monotone transformation (log) for both
> samples and redo the wilcoxon test.
> But since the transformations keeps the order of your samples
> the second wilcoxon test is identical to the first one:
>
> x<-rgamma(10, 2.5, scale = 10)
> y<-rgamma(10, 2.5, scale = 10)
> wilcox.test(x, y, var.equal = FALSE)
> x1<-log(x)
> y1<-log(y)
> wilcox.test(x1, y1, var.equal = FALSE)
>
> Maybe you can give some more details about the hypothesis you'd
> like to test.
>
> Regards,
>
> Christoph Buser
>
> --------------------------------------------------------------
> Christoph Buser <buser@stat.math.ethz.ch>
> 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/
> --------------------------------------------------------------
>
>
>
> > Hi R Users
> >
> >
> > This is a code I wrote and just want to confirm if the first 1000 values
> are raw
> > gamma (z) and the next 1000 values are transformed gamma (k) or not. As I
> get
> > 2000 rows once I import into excel, the p - values beyond 1000 dont look
> that
> > good, they are very high.
> >
> >
> > --
> > sink("a1.txt");
> >
> > for (i in 1:1000)
> > {
> > x<-rgamma(10, 2.5, scale = 10)
> > y<-rgamma(10, 2.5, scale = 10)
> > z<-wilcox.test(x, y, var.equal = FALSE)
> > print(z)
> > x1<-log(x)
> > y1<-log(y)
> > k<-wilcox.test(x1, y1, var.equal = FALSE)
> > print(k)
> > }
> >
> > ---
> > any suggestions are welcome
> >
> > thanks
> >
> > -devarshi
> >
> > ______________________________________________
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