[RkWard-devel] wilcoxon & ansari_bradley tests

[Thomas Friedrichsmeier]

On Sunday 04 February 2007 20:24, SJR wrote:
> > - Does this note recommed turning on the "compute exact p-value" option,
> > or does it recommed to use the exact version of the test? I don't have
> > any background knowledge on the difference between these two.
>
> By default an asymptotic p-value is calculated but it's recommended to use
> the exact option (within this test) if there are less then 50 values and if
> there is no binding (Don't know if this is the right term German:
> "Bindung"). If n < 50 and if there is binding one should use the
> wilcoxon.exact() test (exactRankTests package) for correct results. Hope
> this answers your question.

I see. One last suggestion then: In the documentation for wilcox.test and 
ansari.test, it says "By default (if exact is not specified), an exact 
p-value is computed if both samples contain less than 50 finite values and 
there are no ties. Otherwise, a normal approximation is used." So why not 
just make use of this. I.e. instead of a checkbox, provide a radio with three 
options:

Compute exact p-value
* Yes
* Automatic
* No

In the automatic case (default), the exact=... parameter would be omitted.

Does this sound reasonable?

Regards
Thomas
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