[R] Wilcoxon nonparametric p-values
cvandy26 at gmail.com
Tue May 19 02:21:27 CEST 2009
When I use wilcox.test, I get vastly different p-values than the problems
from Statistics textbooks.
The following problem comes from "Applied Statistics and Probability for
Engineers", 2nd Edition, by D. C. Montgomery. Page736, problem 14.7. The
problem is to compare the sample data with a population median of 8.5. The
book answer is p = 0.25, wilcox.test answer is p = 0.573.
I've tried several other similar problems with similar results. I've copied
the following directly from my workspace.
Thanks for any help,
Wilcoxon signed rank test with continuity correction
V = 80.5, p-value = 0.573
alternative hypothesis: true location is not equal to 8.5
1: In wilcox.test.default(x, y = NULL, mu = 8.5) :
cannot compute exact p-value with ties
2: In wilcox.test.default(x, y = NULL, mu = 8.5) :
cannot compute exact p-value with zeroes
Charles H Van deZande
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