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Understanding Effect Size with Cohen's d
Formula
Effect size measures the magnitude of a difference between groups, independent of sample size. While p-values tell you whether a difference is statistically significant, effect size tells you how large that difference is.
Cohen's d is one of the most common effect size measures, expressing the difference between two group means in standard deviation units.
Common use cases:
- Research study impact assessment
- Meta-analysis across studies
- Statistical power analysis planning
Frequently Asked Questions
Dr. David Park
Applied Mathematician, PhD Mathematics
David holds a PhD in Applied Mathematics from MIT. He has published research on numerical methods and computational algorithms used in engineering and scientific calculators.
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