Free ANOVA F-Ratio Calculator
Calculate the ANOVA F-ratio from between-group and within-group mean squares to test whether group means differ significantly.
F-Ratio
4.0000
df Between2
df Within27
Eta-squared (approx)0.2286
F-Ratio vs Mean Square Between (MSB)
How to Calculate the ANOVA F-Ratio
Formula
F = MSB / MSW
ANOVA (Analysis of Variance) tests whether the means of three or more groups are equal. MSB (Mean Square Between) measures variability between group means. MSW (Mean Square Within) measures variability within groups. A large F-ratio means between-group differences are large relative to within-group noise.
Example Calculation
Three groups, 30 total observations. MSB = 120, MSW = 30.
- 01F = MSB / MSW = 120 / 30 = 4.0
- 02df between = 3 - 1 = 2
- 03df within = 30 - 3 = 27
- 04Eta-squared = (120*2) / (120*2 + 30*27) = 240 / 1050 = 0.2286
- 05About 22.9% of total variance is explained by group membership
Frequently Asked Questions
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