ANOVA

One-way and factorial ANOVA without code

ANOVA compares three or more group means. The arithmetic is the easy part; the friction is choosing the right variant, checking the assumptions, and turning the result into a table and a post-hoc comparison you can defend. Magic Stat keeps all of that in one window.

The honest part

Which ANOVA, and when it is the wrong one

One-way ANOVA tests whether the means of three or more independent groups are equal, by comparing the variation between groups with the variation inside them. That ratio is the F statistic. Welch's ANOVA relaxes the equal-variance assumption and is the safer choice when the groups differ in spread or in size — the same logic as Welch's t for two groups.

When the response is not roughly normal, the rank-based routes are Kruskal-Wallis and Mood's median test, and a permutation F test is available as a check that does not rely on a distributional formula. For two factors at once, the factorial ANOVA adds the interaction term — the question of whether the effect of one factor depends on the level of the other — and Magic Stat computes it with Type III sums of squares. The non-parametric counterpart of the two-way design, Scheirer-Ray-Hare, tests the interaction too.

Designs beyond the simple one-way are where general-purpose tools usually stop: a nested (hierarchical) design, where each level of one factor belongs to exactly one level of another, and block designs such as the Latin square, the 2×2 crossover and the balanced incomplete block. Those are in the same dialog, with the sums-of-squares decomposition each design requires.

What it does

What Magic Stat gives you for ANOVA

How it works

From a spreadsheet to an ANOVA table

  1. Load your data. the response in one column, the grouping factor (three or more levels) in another.
  2. Open Statistics → Means Comparison Tests. and choose Multiple Means for a one-way design.
  3. For more than one factor. click the "Factorial & Repeated Measures ANOVA" button and use the Two-way, Nested or Block Designs tab.
  4. Set the analysis. test family (classical, Welch or rank-based), the post-hoc method, and whether you want effect sizes and confidence intervals.
  5. Read and export. the omnibus table, the post-hoc comparisons and the report, to .docx/.html/.md.
Options

The settings, out in the open

One-way family: One-way ANOVA (equal variances) · Welch's ANOVA (unequal variances) · Kruskal-Wallis · Mood's median test · permutation test.

Post-hoc: Tukey HSD · Bonferroni · Dunn-Sidak · Games-Howell · Dunn's test · Conover-Iman · Dunnett (vs control), with a compact letter display.

Factorial: Type III sums of squares with the interaction, or the non-parametric Scheirer-Ray-Hare; partial eta-squared for A, B and A×B.

Other designs: nested (hierarchical) two levels · Latin square · 2×2 crossover · balanced incomplete block.

Frequently asked

ANOVA questions, answered honestly

One-way or Welch's ANOVA?

Welch's does not assume equal variances and is the safer default when the groups differ in spread or size. The classical one-way F is exact when the variances are equal and the design is balanced. Both are offered, so you can see whether the conclusion depends on the assumption.

Which post-hoc should I use?

Tukey HSD for equal variances and a balanced design; Games-Howell when variances or sizes differ; Bonferroni or Dunn-Sidak when you want a conservative correction for any design; Dunn or Conover-Iman after Kruskal-Wallis; Dunnett when every group is compared against a control. The dialog lists them with their assumptions.

What if the data are not normal?

For one factor, Kruskal-Wallis or Mood's median test; for two factors with an interaction, Scheirer-Ray-Hare tests the interaction as well. A permutation F test is also available. The app reports the choice rather than making it silently.

I have two factors, not one.

Use the factorial tab of the ANOVA dialog. It computes a two-way ANOVA with Type III sums of squares and the interaction term, and partial eta-squared for each effect.

Is ANOVA the right tool for repeated measures?

Not the same one-way dialog — the same subjects measured several times need the repeated-measures route, where the within-subject structure is handled explicitly. That lives in the Repeated Measures tab of the same ANOVA window.

Post-hoc tests → Planned contrasts → ANCOVA → Non-parametric tests →