Statistics

Power Analysis Calculator

Estimate statistical power for a one-sample test.

Calculated Output

Statistical power (%) 78.191

Formula: power = normal CDF of (d*sqrt(n) - z_alpha/2)

Step-by-Step Breakdown

1. Values used:

2. Effect size (Cohen's d) = 0.5

3. Sample size = 30

4. Significance level = 0.05

6. Statistical power = 78.191%

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The math behind it

Power rises with effect size, sample size and alpha. Researchers usually target at least 80%.

d 0.5, n 30, alpha 0.05 gives about 75% power.

What if power is too low?

Increase the sample size or expect a larger effect.