4. A portion of the abstract to a recent study about a new vaccine for the H1N1 virus that was published in a medical journal reads: Design: Double-blind, randomized block design, blocked by age (3-10, 11-18, 19-45, 45-80). Three different factors are present: 20 mg of vaccine, 40 mg of vaccine and a placebo. Prior to the administration of the vaccine, subjects were exposed to high levels of the H1N1 virus. Twenty days after treatment was administered, a blood analysis was performed to determine the effectiveness of the treatment Subjects: 2,300 healthy subjects volunteered: 300 aged 3-10 500 aged 11-18 800 aged 19-45 700 aged 45-80. Provide a diagram of this experiment What are the experimental units? What are the factors? What are the levels? What is the response variable? How many treatments are there? Is there a control group, if so what is it? Is there a placebo, if so what was it?