[R] Problem to interpret wilcox.test

[Peter Dalgaard BSA]

Emmanuel POIZOT <poizot at intechmer.cnam.fr> writes:

> I've got two set of data :
> 22.45 21.56 20.48 19.59 21.52 = A
> and
> 22.15 21.98 20.42 20.58 19.61 = B
> I perform a wilcox.test on this two set
> wilcox.test(A, B) and I'd this answer:
> 
>         Wilcoxon rank sum test
> 
> data:  A and B
> W = 12, p-value = 1
> alternative hypothesis: true mu is not equal to 0
> 
> Should I interpret that there is no difference between the two sets ?

In a word, yes. No *detectable* difference that is. What the p-value
is saying is that there is no way of getting a W closer to the value
expected under the hypothesis of no difference (which is 12.5 in this
case).

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To: r-help-request at stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._