What is statistical power?
Before starting a study, researchers check to make sure there is a good likelihood their study plan will lead to definitive results. An important consideration is whether the study’s statistical analyses are likely to show an association between the potential exposure and the health outcome, if such an association exists. This concept is called statistical power. Statistical power calculations are most often used as a tool for deciding on the appropriate size for a study, and 80% power is the standard.1 Researchers use the power calculations to plan a study that will be large enough to have an 80% probability of showing a statistically significant result, if there is indeed an association between the exposure and disease. In order to estimate study power, researchers first make decisions about study design, study time frame and statistical tests. They have to estimate the numbers of expected health outcomes and the level of increased risk possibly associated with the exposure. They als
