Power Analysis Calculator

Estimate the required sample size per group to achieve a desired statistical power for a two-sample z-test.

Sample Size per Group

31.40

Total Sample Size (2 groups)62.81
Target Power (%)80

Sample Size per Group vs Effect Size (Cohen's d)

सूत्र देखें →

सूत्र

## How to Perform a Power Analysis ### Formula **n per group = ((z_alpha/2 + z_beta) / d)^2** Power is the probability of correctly rejecting a false null hypothesis (detecting a real effect). This formula estimates the sample size needed per group for a two-sample test. Higher power, smaller effect sizes, and lower alpha all require larger samples.

हल किया गया उदाहरण

Detect a medium effect (d = 0.5) with 80% power at alpha = 0.05.

  1. 01n = ((1.96 + 0.842) / 0.5)^2
  2. 02= (2.802 / 0.5)^2
  3. 03= 5.604^2
  4. 04= 31.4
  5. 05Round up: 32 per group, 64 total