10.6 Tests for k Independent Samples

These tests aim to assess if k independent samples come from the same population. Among the most common tests for more than two independent samples, we have the χ2 test for nominal or ordinal variables and the Kruskal-Wallis test for ordinal variables.

10.6.1 The χ2 Test for k Independent Samples

While in Section 10.2.2, the χ2 test was applied to a single sample, in Section 10.4.1 this test was applied to two independent samples. In both cases, the variable(s) is(are) qualitative (nominal or ordinal). The χ2 test for k independent samples (k ≥ 3) is a direct extension of the test for two independent samples.

The data are made available in a contingency table I × J. While the rows represent the different ...

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