A researcher measures systolic blood pressure in 60 hypertensive patients before starting an exercise programme and again after 6 months in the same patients. The differences are normally distributed. The appropriate test to compare the paired readings is:
- A Independent samples t-test
- B Chi-square test
- C Paired t-test ✓
- D One-way ANOVA
Correct answer: C. Paired t-test
Explanation
When the same subjects are measured twice and the differences between paired observations are normally distributed, the paired t-test on the mean difference is the correct test. The independent samples t-test applies to two separate unrelated groups, so it ignores the within-subject correlation and loses power. Chi-square handles categorical proportions, and ANOVA compares three or more independent group means. Pairing is the feature that dictates the choice here.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
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