Refer to Exercise 8 for a description of a study about the drug ipragliflozin.
Exercise 8
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. The placebo is not described in the journal article, but what might it be?
b. What does it mean that the study is double-blind? How could it be accomplished?
c. What are the explanatory and response variables?
d. What is the conclusion of the study? Does this mean there is causality or only an association between the two variables? Explain.
e. In the journal article, three of the researchers report that they are employees of the company that manufactures ipragliflozin. Why is it important that this is stated in the article?