How are Type I and Type II Errors Related to Significance Levels and Power?

The significance level (α) is the probability of making a Type I error. Commonly, researchers use a significance level of 0.05, meaning there is a 5% risk of concluding that an effect exists when it does not. The power of a statistical test is the probability of correctly rejecting a false null hypothesis, which is 1 minus the probability of making a Type II error (β). Higher power indicates a lower likelihood of making a Type II error. Power is often set at 0.80 or 80%, meaning there is an 80% chance of detecting an effect if there is one.