In a clinical trial comparing two proportions, the type II error (β) is set at 0.20. The statistical power of the study is:
- A 20%
- B 80% ✓
- C 95%
- D 0.20
Correct answer: B. 80%
Explanation
Power = 1 – β (Type II error). With β = 0.20, Power = 1 – 0.20 = 0.80 = 80%. Power is the probability of correctly rejecting the null hypothesis when it is truly false (i.e., correctly detecting a real difference). A power of 80% is the conventional minimum for clinical trials. Type I error (α) is the probability of a false positive; typically set at 0.05. Increasing sample size, effect size, or α increases statistical power.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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