When I use wilcox.test, I get vastly different p-values than the problems from Statistics textbooks. For example: 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, CHV > x<-c(8.32,8.05, > 8.93,8.65,8.25,8.46,8.52,8.35,8.36,8.41,8.42,8.30,8.71,8.75,8.6,8.83,8.5,8.38,8.29,8.46) > wilcox.test(x,y=NULL,mu=8.5) Wilcoxon signed rank test with continuity correction data: x V = 80.5, p-value = 0.573 alternative hypothesis: true location is not equal to 8.5 Warning messages: 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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