Systolic blood pressure is recorded in 60 hypertensive patients before starting a lifestyle modification programme and again after 6 months in the same patients. The investigator wants to know whether the mean change is statistically significant. The most appropriate test is:
- A Paired t-test ✓
- B Unpaired Student t-test
- C Chi-square test
- D Z-test of two proportions
Correct answer: A. Paired t-test
Explanation
The two sets of readings come from the same individuals measured before and after an intervention, so the observations are paired and correlated. The paired t-test compares the mean of within-subject differences against zero. The unpaired t-test is for two independent groups, which is what makes option B tempting when students see two columns of numbers rather than recognising that both columns belong to the same 60 subjects.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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