ANOVA (F-statistic) and Kruskal-Wallis (H-statistic)

The one-way ANOVA has several assumptions:

The F-statistic results from performing ANOVA.

Consider the evaluation data in the evals.sav file. For the analysis on whether students' evaluations of instructors are determined by the students' expected grades, the dependent variable is not interval. As a result, it is not legitimate to examine this question with ANOVA.

An applicable statistic is the Kruskal-Wallis, which has the following assumptions:

Kruskal-Wallis reports an H-statistic (interpretable in much the same way that the F-statistic is interpreted). Note that Kruskal-Wallis does not require interval data.  To determine the general shape of data, either examine them graphically or perform descriptive statistics on the two groups to make sure they are similar.

To access Kruskall-Wallis in SPSS,

  1. Select "Analyze" then "Nonparametric Tests" then "K Independent Samples"
  2. Select one or more numeric variables
  3. Select a grouping variable
  4. Click "Define Range" to specify minimum and maximum integer values for the grouping variable.