Power analysis factors include which elements?

Power analysis factors include which elements?

• A. Data collection time, budget, and personnel.
• B. Number of variables and missing data rate.
• C. Reliability of measures and validity coefficients.
• D. Expected effect size, significance level, and desired power.

Answer: (D)

Power analysis tells you how large a sample you need to detect a real effect with a chosen level of confidence. The three inputs that enter directly are the expected effect size, the significance level (alpha), and the desired power (1 minus beta). If you anticipate a small effect, you’ll generally need more participants; increasing alpha lowers the required sample size but raises the chance of a false positive; aiming for higher power raises the needed sample size because you want a greater chance of detecting the effect if it truly exists. Logistical factors like data collection time, budget, and personnel affect feasibility but aren’t the fundamental inputs used to compute power. Measurement quality matters in practice because unreliable measures dampen observed effects, and missing data reduces usable sample size, but the essential factors you choose for the power calculation are effect size, alpha, and desired power.

Power analysis tells you how large a sample you need to detect a real effect with a chosen level of confidence. The three inputs that enter directly are the expected effect size, the significance level (alpha), and the desired power (1 minus beta). If you anticipate a small effect, you’ll generally need more participants; increasing alpha lowers the required sample size but raises the chance of a false positive; aiming for higher power raises the needed sample size because you want a greater chance of detecting the effect if it truly exists. Logistical factors like data collection time, budget, and personnel affect feasibility but aren’t the fundamental inputs used to compute power. Measurement quality matters in practice because unreliable measures dampen observed effects, and missing data reduces usable sample size, but the essential factors you choose for the power calculation are effect size, alpha, and desired power.