A study measures pain scores on a visual analog scale (0-10) before and after physiotherapy in 12 patients with chronic low back pain. The differences are not normally distributed. Which test is most appropriate to compare pre- and post-treatment scores?

• A Paired t-test
• B Independent-samples t-test
• C Mann-Whitney U test
• D Wilcoxon signed-rank test ✓

Explanation

The Wilcoxon signed-rank test is the non-parametric alternative to the paired t-test, used for paired data when the differences are not normally distributed. The Mann-Whitney U test is for two independent groups, and the paired t-test requires normally distributed differences. The data are paired because the same patients are measured twice.

Reference: Methods in Biostatistics, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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