Bonett's test for equal variances (k ≥ 2 groups): Layard's statistic on ln sᵢ² with the
kurtosis-adjusted variances of Bonett (2006), T = Σ wᵢ (ln sᵢ² − c̄)², wᵢ = (nᵢ − 1)/(γ̂ − (nᵢ − 3)/nᵢ),
χ² with k − 1 df — robust to non-normality, the basis of Minitab's "multiple comparisons" test.
Bonett's test for equal variances (k ≥ 2 groups): Layard's statistic on ln sᵢ² with the kurtosis-adjusted variances of Bonett (2006), T = Σ wᵢ (ln sᵢ² − c̄)², wᵢ = (nᵢ − 1)/(γ̂ − (nᵢ − 3)/nᵢ), χ² with k − 1 df — robust to non-normality, the basis of Minitab's "multiple comparisons" test.