This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Biostatistics, Subject name: Social & Preventive Medicine
In a clinical trial, blood pressure was measured in a group of patients before and after treatment, which of the following tests will be suitable as a test of significance: 
Select and explain. 
A. Paired t-test, B. Mann-Whitney U test, C. Student t-test, D. ANOVA
A: Paired t-test
Answer: A: Paired t-test 
Explanation: Ans. A. Paired t-testUnpaired t-test (aka Students test) compares two different subjects. The paired t-test reduces intersubject variability (because it makes comparisons between the same subject), and thus is theoretically more powerful than the unpaired t-test.In our case, we are analyzing the same subject twice (that is before and after).