Your comparison
Cohen's d for two groups. Enter the means, standard deviations and group sizes.
—
Cohen's d
0.51
Also useful
- Hedges' g (small-sample corrected)—
- Pooled SD—
- Mean difference—
- Total N—
How to report it
Why examiners ask for this
- Significance is not size. With a large enough sample almost any difference reaches p < .05. The effect size is what tells a reader whether it matters.
- Cohen's benchmarks are generic. Small, medium and large were offered as rough guides across the social sciences. In your specific field the conventional bar may be higher or lower — check comparable published studies.
- Use Hedges' g for small samples. Below roughly 20 per group, Cohen's d is biased upwards; g corrects for it.
- Report it for every comparison, not only the significant ones. Selective reporting of effect sizes is as visible as selective reporting of fit indices.
Not sure this is the right calculation for your design? Send us your design and we will tell you which rule applies — at no charge.
Ask about your design