Question:

A study was performed comparing the efficacy of two anti-hypertensive (blood pressure reducing) medications, A and B, on 117 hypertensive individuals. The systolic blood pressure (sbp) measurements were taken over the course of three days after 20 days treatment.

Changes in systolic blood pressure (in mm Hg) are tabulated below:

Note: you can assume equal variances among the three groups

a) Is the mean change in sbp the same among all three groups?

b) Does any of the medications (either A or B or both) have a significant effect on sbp reduction?

c) Is there a significant difference between the effects (if any) of medications A and B in lowering sbp?