proportionZTestPower
Computes the statistical power of a proportion z-test using the normal approximation.
Power is the probability of correctly rejecting the null hypothesis when the true effect size equals effectSize. Uses Cohen's h as the effect size metric, which is based on the arcsine transformation of proportions. Conventional thresholds: 0.2 (small), 0.5 (medium), 0.8 (large). Negative effect sizes are treated as their absolute value.
Example:
// Power of a two-sample proportion z-test with 64 per group
proportionZTestPower(effectSize = 0.5, n = 64) // ~0.807
proportionZTestPower(effectSize = 0.5, n = 64, twoSample = false) // ~0.979Return
the statistical power, a value in [0, 1].
Parameters
the expected Cohen's h effect size. The sign is ignored.
the sample size. For two-sample tests (twoSample = true), this is the per-group size assuming equal groups. For one-sample tests, this is the total sample size. Must be at least 2.
the significance level (Type I error rate). Defaults to 0.05 (5%). Must be in (0, 1).
the direction of the alternative hypothesis. Defaults to Alternative.TWO_SIDED.
whether this is a two-sample test. Defaults to true. When false, uses the one-sample noncentrality factor (higher power for the same n).
See also
to find the sample size needed for a target power.
to find the smallest detectable effect at a given sample size.
to compute Cohen's h from two proportions.