Review Question - QID 217044

The researchers are attempting to determine whether the mean GFR, which is a normally distributed (Gaussian) variable, differs across 3 groups. The most appropriate test is thus the analysis of variance (ANOVA).

To compare the means of normally distributed continuous variables, the appropriate statistical test to use depends on the number of groups being compared. When 2 groups are being compared, the t test is used. When more than 2 groups are being compared, the ANOVA test is used. The null hypothesis in the ANOVA test is: there is no difference in the means between the groups being compared. The ANOVA test yields a p-value that is then compared to the predetermined significance level (e.g., 0.05) to determine whether the null hypothesis is rejected.

Incorrect Answers:
Answer 2: Chi square tests are used to compare categorical variables (e.g., count data) between 2 or more groups. For example, a chi square test could be used to compare whether there is a difference in sex distribution between the groups.

Answer 3: The Kruskal-Wallis test is a non-parametric version of the ANOVA test that is used for non-normally distributed (non-Gaussian) variables.

Answer 4: The Pearson correlation coefficient is a measure of association between 2 continuous variables. For example, it could be used to characterize the relationship between GFR and the serum concentration of an ACE inhibitor at a predetermined point in time.

Answer 5: The t test is used to compare normally distributed continuous variables between 2 groups. For example, it could be used to compare whether GFR differs between white and non-white participants.

Bullet Summary:
The analysis of variance (ANOVA) test is used to compare the means of normally distributed continuous variables between more than 2 groups.