nonparam
Kruskal–Wallis
Compare three or more independent groups using ranks.
Requirements
- ordinal or continuous outcome
- categorical group with 3+ levels
Avoid when
- paired/repeated designs
- need adjusted covariates
Formula
H = 12/[N(N+1)] Σ(Rⱼ²/nⱼ) − 3(N+1)
Interpretation
Global rank-based group difference; follow with corrected post-hoc tests.
Worked example
Compare skewed recovery times across three independent treatment groups.
Open example datasets