Reconsider the port alcohol content data from Exercise 14.22. A normal probability plot casts some doubt on the assumption of population normality. However, a dotplot shows a reasonable amount of symmetry, and the mean, median, and 5% trimmed mean are 19.257, 19.200, and 19.209, respectively. Use the Wilcoxon test at significance level .01 to decide whether there is substantial evidence for concluding that true average content exceeds 18.5.
Exercise 14.22. The article "A Method for the Estimation of Alcohol in Fortified Wines Using Hydrometer Baumé and Refractometer Brix" (Amer. J. of Enol. and Vitic., 2006: 486-490) gave duplicate measurements on distilled alcohol content (%) for a sample of 35 port wines. Here are averages of those duplicate measurements Use the Ryan-Joiner test to decide at significance level .05 whether a normal distribution provides a plausible model for alcohol content.