How to Use the One-Way ANOVA Calculator
When you want to check whether three or more group means differ from each other, running repeated t-tests isn't the right approach — you need one-way ANOVA instead. Enter each group's data and this calculator computes between-group variance, within-group variance, and the F-statistic that compares them.
Between-group variance (SSB) measures how far each group's mean is from the overall grand mean, while within-group variance (SSW) measures how spread out the data is within each group around its own mean. Dividing each by its degrees of freedom (k-1 for between-groups, N-k for within-groups) gives the mean squares (MS), and the ratio of these two mean squares is the F-statistic.
A larger F-value means the differences between groups are large relative to the random variation inside each group, which suggests a real difference is more likely. Confirming statistical significance still requires comparing your F-value against a critical value from an F-distribution table, so this calculator provides the F-value along with a rough interpretive guide.
Frequently Asked Questions
The F-statistic is between-group variance divided by within-group variance. A larger F means the differences between group means are large relative to the random variation within each group, suggesting a real difference between groups. Confirming statistical significance requires comparing it to a critical value from the F-distribution.
This calculator supports up to 3 groups, and one-way ANOVA works with a minimum of 2 groups. Leave the third group field blank to calculate with just 2 groups.