A Type II error (β error) in a clinical trial means:
- A Concluding the treatment works when it actually does not
- B Selecting a biased sample from the target population
- C Failing to detect a true treatment effect that actually exists ✓
- D Using the wrong statistical test for the data type
Correct answer: C. Failing to detect a true treatment effect that actually exists
Explanation
Type II (β) error is a false negative — accepting the null hypothesis when it is actually false, i.e., failing to detect a real treatment effect. Type I (α) error is a false positive — rejecting the null hypothesis when it is actually true. Study power = 1 − β; typical acceptable β is 0.20 (80% power). Sample size calculations are designed to keep both α and β within acceptable limits. Reducing sample size increases β error.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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