About this calculator
Free ANOVA calculator for comparing means across multiple groups. Calculate F-statistic, sum of squares, and determine statistical significance.
How to use
Enter your values in the fields above and click Calculate to see your results. Click Clear to reset all fields.
Frequently Asked Questions
What sample size do I need for reliable results?
It depends on the test and the effect size you expect. As a rough guide: t-tests need n ≥ 30 per group, chi-square needs ≥ 5 expected in each cell, regression needs n ≥ 10-20 per predictor. Use a power analysis tool before data collection to determine the minimum sample size for your required confidence level and effect size.
What does statistical significance actually mean?
A p-value below your threshold (typically 0.05) means there is less than a 5% probability of observing results this extreme if the null hypothesis were true. It does NOT mean the effect is large, important, or that the null hypothesis is false — just that your data are unlikely under that assumption. Always interpret significance alongside effect size.
When should I use this test vs. alternatives?
Each statistical test has specific assumptions about data distribution, sample independence, and measurement scale. Violating these assumptions can produce misleading p-values. Check: is your data normally distributed? Are observations independent? Is the measurement scale appropriate? If assumptions are violated, consider a nonparametric alternative.
How do I report these results correctly?
Report the test statistic, degrees of freedom, p-value, and effect size. For example: t(28) = 2.45, p = .021, d = 0.89. Don't just report p < 0.05 — include the exact p-value, the full test result, and a plain-language interpretation. Always report confidence intervals alongside point estimates.