Using Cohen’s D for Experiments

Nina Zumel takes us through Cohen’s D, a useful tool for determining effect sizes in experiments:

Cohen’s d is a measure of effect size for the difference of two means that takes the variance of the population into account. It’s defined as
d = | μ₁ – μ₂ | / σ_pooled
where σ_pooled is the pooled standard deviation over both cohorts.

Read the whole thing.