Which of the following statements are necessary to increase statistical power?

A. Increasing the sample size
B. Using two-tailed test
C. Increasing the alpha level
D. Decreasing the variability among participants
E. Increasing the magnitude of treatment

Correct option is B

Statistical power refers to the probability of correctly rejecting a false null hypothesis (avoiding a Type II error). To increase statistical power, the following factors are essential:
    A. Increasing the sample size: Larger sample sizes reduce sampling error, leading to more accurate estimates and increased power.
    C. Increasing the alpha level: Raising the significance level (e.g., from 0.01 to 0.05) makes it easier to reject the null hypothesis, thereby increasing power.
    D. Decreasing variability among participants: Reducing variability improves the precision of estimates, which enhances power.
    E. Increasing the magnitude of treatment: A stronger effect size makes it easier to detect differences, thereby increasing power.

Additional Knowledge
Why Two-Tailed Tests Don’t Increase Power:
Two-tailed tests require stronger evidence to reject the null hypothesis since the critical regions are split between both tails, reducing power compared to one-tailed tests.