Statistical power is defined as the probability of what?

Statistical power is defined as the probability of detecting a true difference when it exists. This means that if there is indeed an effect or a difference in the population being studied, the statistical power indicates the likelihood that a study will successfully identify that difference through its analysis. A higher statistical power reduces the risk of making a Type II error, which occurs when a study fails to reject the null hypothesis when it should have, meaning it overlooks a true effect.

The significance of statistical power lies in its influence on study design and sample size: higher power typically requires larger sample sizes, thereby enhancing the reliability and validity of research findings. Power is influenced by several factors including sample size, effect size, and significance level, each contributing to the likelihood of finding a true effect when it exists. This is essential for ensuring that research findings are not due to chance and can be confidently generalized to the larger population.