The critical value is taken from the F-distribution whenever the test is a Kruskal-Wallis test.

F-distribution

A probability distribution used in analysis of variance (ANOVA), especially relevant when comparing variances across different samples.

Kruskal-Wallis Test

A non-parametric statistical test that compares three or more independent samples to determine if at least one sample distribution stochastically dominates one other sample.

Critical Value

A threshold value used in hypothesis testing which separates the region where the null hypothesis is rejected from the region where it is not rejected.