A cholesterol test was given to 10 heart patients with high cholesterol levels.The same 10 heart patients are then given a new cholesterol-reducing drug for six months.Before the patients begin taking the drug,they are told to maintain their current diets and eating habits so that the effect of the drug can be more effectively determined.After taking the drug for six months,the same patients are given a cholesterol test again.The pharmaceutical company manufacturing the medicine wants to know if the drug is effective in reducing the cholesterol levels of the patients.The cholesterol levels before and after taking the drug are recorded for each patient.The population of cholesterol levels is not normally distributed.Which one of the following nonparametric tests is appropriate for this problem?
A)Wilcoxon signed ranks test
B)Wilcoxon rank sum test
C)Sign test
D)Kruskal-Wallis test
E)Spearman's rank correlation test

Question

Quizplus · Accepted Answer

The Wilcoxon signed ranks test is appropriate for this problem because it is used to test the null hypothesis that the population median of a paired difference is equal to zero. In this case, we are interested in comparing the cholesterol levels before and after taking the drug for the same patients. Since the population of cholesterol levels is not normally distributed, a nonparametric test, such as the Wilcoxon signed ranks test, should be used. The other options are not appropriate for this problem. The Wilcoxon rank sum test is used to compare two independent samples, the sign test is used to test the null hypothesis that the median of a population is equal to a hypothesized value, the Kruskal-Wallis test is used to compare more than two independent samples, and Spearman's rank correlation test is used to test the strength of the relationship between two variables.

A Cholesterol Test Was Given to 10 Heart Patients with High