Power Analysis Calculator

Compute the sample size needed to detect a given effect size (Cohen's d) at any α and power for a one-sample z-test.

Frequently Asked Questions

What is power analysis?

The process of determining the sample size needed to detect an effect of a given size with a chosen significance and power level.

What is Cohen's d?

Standardized effect size: (mean - hypothesized mean) / SD. Conventional cutoffs: 0.2 small, 0.5 medium, 0.8 large.

Is 80% power standard?

Yes - the conventional minimum. Higher (90%, 95%) reduces Type II errors but requires bigger samples.

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Estimates for informational purposes only.

Important Disclaimer: Estimates for informational purposes only.

This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.

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