A study showed that low-intensity vibration therapy reduces pain levels in patients with fibromyalgia. During each session in the study, vibration pads were placed on the pain site indicated by the patient. Pain reduction was measured through self-reporting after each session. Another study is being designed to examine whether low-intensity vibration therapy also reduces pain in patients suffering from ruptured disks in the lumbar region of the back. Three hundred male patients are subjects in the new study.

Part A: What is an appropriate design for the new study? Include treatments used, method of treatment assignment, and variables that should be measured. (4 points)

Part B: If the study consisted of 150 male and 150 female patients instead of 300 male patients, would you change the study design? If so, how would you modify your design ? If not, why not? (4 points)

Part C: Could your design be double-blind? Explain.