[R] wilcox.exact() problem

Peter Dalgaard p.dalgaard at biostat.ku.dk
Wed Oct 28 19:51:08 CET 2009

Achim Zeileis wrote:
> On Wed, 28 Oct 2009, David Croll wrote:

>> Am I paranoid, or am I in search of an exactness statistics cannot 
>> deliver?
> Paranoid. ;-) With your sample size all solutions should be sufficiently 
> close to exact.

Well, the world could still be out to get him... It is required that 
proper tie corrections are applied. Otherwise, the variance of the test 
statistic is overestimated and p-values inflated. They are applied in 
wilcox.test, so no need to worry. (I think stats packages that do not do 
tie corrections would be hard to come by these days.)

    O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
   c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
  (*) \(*) -- University of Copenhagen   Denmark      Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)              FAX: (+45) 35327907

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