Effect Size Calculator

Effect size measures the practical significance of a result independent of sample size. A statistically significant result can have a trivially small effect size — effect size tells you whether it matters.

1. 1Cohen's d = (Mean₁ − Mean₂) / Pooled SD
2. 2Small: d = 0.2; Medium: d = 0.5; Large: d = 0.8
3. 3r = d / √(d² + 4) converts d to correlation
4. 4η² (eta-squared) used for ANOVA effect size