Which level is typically considered acceptable for statistical power?

Which level is typically considered acceptable for statistical power?

• A. 50–60%
• B. 60–70%
• C. 80–90%
• D. 95–100%

Answer: (C)

Power is the probability of detecting a true effect if one exists. In study planning, researchers commonly aim for power around 0.80 to 0.90 because this range provides a good balance between reliably finding real effects and keeping the required sample size feasible. A power of 0.80 means an 80% chance of detecting the effect when it’s truly there (limiting the risk of a Type II error to 20%). Levels like 50–60% are too low, increasing the chance of missing real effects, while 95–100% is typically impractical for most public health studies and often unnecessary. That pragmatic middle ground—80–90%—is why it’s considered acceptable.

Power is the probability of detecting a true effect if one exists. In study planning, researchers commonly aim for power around 0.80 to 0.90 because this range provides a good balance between reliably finding real effects and keeping the required sample size feasible. A power of 0.80 means an 80% chance of detecting the effect when it’s truly there (limiting the risk of a Type II error to 20%). Levels like 50–60% are too low, increasing the chance of missing real effects, while 95–100% is typically impractical for most public health studies and often unnecessary. That pragmatic middle ground—80–90%—is why it’s considered acceptable.