stats
Friedman Test
Non-parametric RM-ANOVA — rank matrix heatmap, χ²_r statistic, Kendall W, Conover post-hoc.
Non-parametric alternative to Repeated Measures ANOVA — use when data is ordinal or normality/sphericity assumptions are violated.
Design
S1S2S3S4
Complete data required for all cells — Friedman test cannot proceed with missing values.
Friedman Test Results
χ²_r statistic—
df—
p-value—
Kendall's W—
Conclusion α = 0.05—
χ²_r = 12/(nk(k+1)) · Σ R_j² − 3n(k+1) · W = χ²_r / (n(k−1))