A comparative research question always involves the differences between two or more groups with respect to a particular variable. These groups are then distinguished on the basis of a given characteristic. This chapter deals with the statistical tests to be used when both the test variable and the grouping variable are measured at the nominal level. It is concerned with the tests employed when the grouping variable is at least at the nominal level and the test variable at the ordinal level. The chapter discusses that the tests used when the grouping variable is at least measured at the nominal level and the test variable at the interval or ratio level. When more than two groups are involved in students' study, such as those having lower secondary, upper secondary and higher education, the Kruskal-Wallis test can be used. To do this, they select “Analyze” in the main menu and subsequently “Nonparametric Tests”.