Biostatistics & Research · single question
Statistical power of a study is calculated as:
Show answer and explanation
Correct answer: D. 1 - β (1 minus the probability of Type II error)
- A. Type I error / 2 describes a two-tailed significance threshold calculation — not power.
- B. 1 - α relates to the confidence level (e.g., 95% confidence = α of 0.05). This is the confidence interval calculation, not statistical power.
- C. Type II error / 2 is not a standard statistical calculation — power = 1 - β (whole Type II error), not half of it.
- D. Correct. Statistical power = 1 - β, where β is the Type II error rate (false negative — failing to reject a false null hypothesis). Power represents the probability of correctly detecting a true effect when one exists. A study with 80% power has a 20% Type II error rate (β = 0.20).
Practice Biostatistics & Research questions Biostatistics & Research study notes