The Wilcoxon signed-rank test can also be used for paired data by testing if the median difference

Question:

The Wilcoxon signed-rank test can also be used for paired data by testing if the median difference is different from 0 . The data presented in Table 11.14 gives the before and after cholesterol levels (in $\mathrm{mg} / \mathrm{dL}$ ) for a random sample of 11 patients who were given a cholesterol-lowering drug.

a. Using the Wilcoxon signed-rank test, determine if the cholesterol drug was effective in reducing cholesterol.

b. Do you believe that the assumptions underlying the Wilcoxon signed-rank test have been violated?

Table 11.14