The null hypothesis in ANOVA one-way classification, the study of the variances due to k different sources, is:
1. H0 ∶ σ1 = σ2 = ⋯ = σk
2. H0 ∶ At least for one pair μi = μj; i, j = 1, 2…k, i ≠ j
3. H0 ∶ At least for one pair σi = σj; i, j = 1, 2…k, i ≠ j
4. H0 ∶ μ1 = μ2 = ⋯ = μk