A study showed that vitamin E oil reduces pain levels in patients with lupus. During each session, the oil was injected into 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 vitamin E oil also reduces pain in patients suffering from bulging disks in the thoracic region of the back. Two hundred patients aged 20–40 years 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. (5 points)

Part B: If the study consisted of 100 young patients and 100 old patients instead of 200 patients aged 20–40, would you change the study design? If so, how would you modify your design? If not, why not? (5 points)

Part C: Suppose the data in the following table was collected at the end of the study you described in part A.


Vitamin E Oil Placebo
Reported Pain Reduction 52 35
Total Treated 100 100


Construct 90% confidence intervals for the proportion of pain reduction for each treatment group. Show all work. (5 points)

Part D: What can you conclude about the use of vitamin E oil for patients with bulging disks in the thoracic region of the back? (5 points)