Friedman’s ANOVA is used for which data scenario?

• A. Independent normal data
• B. Related samples with ordinal data
• C. Proportions
• D. Categorical outcomes across groups

Answer: (B)

Friedman’s ANOVA is a nonparametric alternative to the repeated-measures ANOVA. It’s used when you have related samples—same subjects measured under several conditions—and the data are ordinal or don’t meet normality. Instead of comparing means, it ranks the data within each subject across the conditions and tests whether those average ranks differ across conditions. A significant result suggests that at least one condition differs from the others. The statistic follows a chi-square distribution with k−1 degrees of freedom, where k is the number of conditions.

This fits best with related samples with ordinal data. If the data were independent and normal, you’d use a parametric ANOVA for repeated measures; if the data were just proportions or nominal categories, you'd use chi-square or related tests rather than Friedman.