A clinical trial comparing two antihypertensive drugs reports a p-value of 0.04 for the primary outcome. The study was powered at 80% with α=0.05. Which statement is most accurate regarding interpretation of this result?
- A The probability that the null hypothesis is true is 4%
- B There is a 4% probability of observing data at least this extreme if the null hypothesis were true ✓
- C The treatment effect is clinically important because p<0.05
- D The study has a 96% probability of replication in a similar future trial
Explanation
The correct interpretation of a p-value is: given that the null hypothesis (no difference) is true, the p-value represents the probability of obtaining a test statistic at least as extreme as the observed result by chance. It does NOT mean the probability that the null hypothesis is true (that would require Bayesian posterior probability). Statistical significance (p<0.05) does not equate to clinical significance — a trivial difference can be statistically significant in a large trial. The power of a study (80%) refers to the ability to detect a true effect, not the replication probability.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
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