# [R] gamma distribution

Wed Jul 27 21:24:43 CEST 2005

```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 at 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 at 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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