Find your way
around StatPower.

Calculate sample size, achieved power, or a minimum detectable effect.

Understand the four quantities behind a power analysis.

See how to interpret the calculator responsibly.

Plain-language guides to the decisions behind a power analysis.

Three defensible ways to pick the effect size for a power analysis, and the mistakes reviewers catch.

A step-by-step worked example, including attrition, covariates, clustering and multiple outcomes.

Why the tool exists, the principles behind it, and its relationship to DASS.

Formulas, assumptions, worked examples, and validation against R for every design.

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How StatPower may be used, and why its results are planning estimates to verify.

Statistical consulting, study design, analysis, and training.

Discuss a complex design or a publication-ready power analysis with DASS.