A paired t-test is used to compare pre- and post-treatment blood pressure measurements in the same group of patients. The assumption underlying this test (compared to independent samples t-test) is:

• A The two groups have equal variances
• B The differences between paired observations are normally distributed ✓
• C The sample size must exceed 30 in each group
• D The outcome variable must follow a Poisson distribution

Explanation

The paired t-test examines the differences (d) between paired observations and tests whether the mean difference is zero. The key assumption is that these differences are approximately normally distributed, not that each measurement independently follows a normal distribution. The independence assumption is relaxed because the two sets of measurements are from the same subjects. No minimum sample size is strictly required if the normality of differences holds.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.