# power

The probability of a hypothesis test correctly detecting a real effect.

**Note 1:** Power is also the probability of avoiding a Type II error and therefore corresponds to (1 - β).

**Note 2:** A power analysis may be performed to determine whether a sample size will have sufficient power to reject a false null hypothesis, and so find the effect described by the alternative hypothesis.

**Note 3:** Related terms include hypothesis testing, beta (β), and statistical power.