By measuring the glycated hemoglobin level in the blood-stream, a doctor can determine what a patient’s average blood sugar level has been in past months. The glycated hemoglobin level of untreated type 2 diabetes patients is too high. Between March 2008 and March 2009, researchers tested whether the drug ipragliflozin decreased glycated hemoglobin levels in Japanese patients with type 2 diabetes at 39 sites in Japan. The drug is in pill form. In the double-blind study, the 361 patients were randomly assigned to 4 treatment groups of different ipragliflozin dosages or a placebo group. The study concluded that the drug successfully lowers glycated hemoglobin levels in Japanese patients with type 2 diabetes.
a. Describe the treatment and control groups.
b. Is the study an experiment or an observational study? Explain.
c. What does random assignment mean in this study? How could this be accomplished?
d. Describe the sample and the population.