Statistics

Cohen's D Calculator

Find Cohen's d effect size from two group means and SDs.

Calculated Output

Cohen's d 0.5432

Formula: d = (m₁ − m₂) ÷ pooled SD

Step-by-Step Breakdown

1. Values used:

2. Mean 1 = 80

3. Mean 2 = 74

4. SD 1 = 10

5. SD 2 = 12

7. Cohen's d = 0.5432

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The math behind it

d = (mean₁ − mean₂) ÷ pooled SD, where pooled SD = √((s₁² + s₂²)/2). 0.2 small, 0.5 medium, 0.8 large.

Means 80 vs 74, SDs 10 and 12 → d ≈ 0.54 (medium).

Effect size vs p-value?

Effect size shows how big a difference is; p-value shows whether it's statistically reliable.