On Sep 13, 2011, at 4:51 PM, Tianchan Niu wrote:
Thank you David for your reply. But I am still confusing.
I am using Wilcoxon test to compare two samples to assess whether
their means differ because neither of them is normally distributed.
Is it possible to compute the power of the Wilcoxon test similar to
that of t test? Or is it just a wrong question?
If you formulate a null hypothesis and alternative that is appropriate
for the test, then yes, you can ask the question "what is the power of
the Wilcoxon signed rank test". But you need to look at the
assumptions of the test, so you can be precise about what is being
tested. I'm thinking you may want to pose your general, non-R question
in a forum that is advertised to consider such tutoring. http://stats.stackexchange.com/
comes to mind immediately.
Thank you!
________________________________________
From: David Winsemius [dwinsem...@comcast.net]
Sent: Tuesday, September 13, 2011 4:24 PM
To: Tianchan Niu
Cc: r-help@r-project.org
Subject: Re: [R] How to calculate the power of Wilcoxon signed rank
test
On Sep 13, 2011, at 3:34 PM, tn85 wrote:
Hello All,
I perform a Wilcoxon signed rank test for two sets of data to test
whether
they two have significantly different means. I would also like to
know the
power of this test.
Given that none of the various "Wilcoxon tests" are for differences in
means, you are proposing it for the wrong purpose.
The third part of this tutorial is similar to what I want except
the t
distribution. http://www.cyclismo.org/tutorial/R/power.html#multiT
Could anyone help? Or let me know if my question is a nonsense one.
Thanks
in advance.
--
David Winsemius, MD
West Hartford, CT
David Winsemius, MD
West Hartford, CT
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