Blood pressure is measured in 60 hypertensive patients before starting an exercise programme and again after 3 months of the same programme. The researcher wants to know whether the mean change within these same individuals is statistically significant. Which test is most appropriate?
- A Unpaired t-test
- B Paired t-test ✓
- C Chi-square test
- D One-way ANOVA
Correct answer: B. Paired t-test
Explanation
The same subjects are measured twice under two conditions (before and after), so the observations are paired, and the paired t-test compares the mean of within-subject differences against zero. The unpaired t-test applies only to two independent groups, which is the trap here. Chi-square handles categorical data, and ANOVA needs three or more independent group means. If the differences themselves were badly non-normal, the Wilcoxon signed rank test would replace it.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
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