Statistical power is a function of

Statistical power is a function of

• A. Significance criterion (alpha), variance in data, and effect size
• B. Variance in data only
• C. Sample size only
• D. Study duration

Answer: (A)

Statistical power is the probability of detecting a true effect if one exists. It increases when the alpha level is higher (a less strict threshold for declaring significance), when the true effect size is larger (a bigger difference is easier to detect), and when data variability is smaller (less noise makes the signal clearer). These factors directly shape how likely a study is to reject the null hypothesis when there really is a difference. While sample size also influences power, the combination that best captures the determinants among the given choices is alpha, variance, and effect size. Variance alone misses how the decision threshold and the size of the effect matter; sample size alone ignores data quality and effect magnitude; study duration doesn’t directly affect the ability to detect a real difference.

Statistical power is the probability of detecting a true effect if one exists. It increases when the alpha level is higher (a less strict threshold for declaring significance), when the true effect size is larger (a bigger difference is easier to detect), and when data variability is smaller (less noise makes the signal clearer). These factors directly shape how likely a study is to reject the null hypothesis when there really is a difference. While sample size also influences power, the combination that best captures the determinants among the given choices is alpha, variance, and effect size. Variance alone misses how the decision threshold and the size of the effect matter; sample size alone ignores data quality and effect magnitude; study duration doesn’t directly affect the ability to detect a real difference.