Peak expiratory flow rate is measured in 50 asthmatic children before and 4 weeks after starting inhaled corticosteroids. To determine whether the change within the same children is statistically significant, the appropriate test is:

• A Unpaired (independent samples) t-test
• B Paired t-test ✓
• C Chi-square test
• D One-way ANOVA

Explanation

The two sets of readings come from the same 50 children, so the observations are paired and correlated. The paired t-test analyses the differences within each child against zero, which removes inter-individual variability and increases statistical power. An unpaired t-test assumes two independent groups and would waste this design advantage. Chi-square handles categorical data, and ANOVA compares three or more independent group means.

Reference: Mahajan's Methods in Biostatistics for Medical Students, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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