In March 2005, the New England Journal of Medicine published the results of a 10-year clinical trial of low-dose aspirin therapy for the cardiovascular health of women (Time, March 21, 2005). The study was based on 40,000 healthy women, most of whom were in their 40s and 50s when the trial began. Half of these women were administered 100 mg of aspirin every other day, and the others were given a placebo. Assume that the women were assigned randomly to these two groups.
a. Is this an observational study or a designed experiment? Explain.
b. From the information given above, can you determine whether or not this is a double-blind study? Explain. If not, what additional information would you need?