Protecting ultramarathon runners. An ultramarathon, as you might guess, is afootrace

Chapter 0, Problem 9.37

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Protecting ultramarathon runners. An ultramarathon, as you might guess, is afootrace longer than the 26.2 miles of a marathon. Runners commonly developrespiratory infections after an ultramarathon. Will taking 600 milligrams ofvitamin C daily reduce these infections? Researchers randomly assignedultramarathon runners to receive either vitamin C or a placebo. Separately, theyalso randomly assigned these treatments to a group of nonrunners the same age asthe runners. All subjects were watched for 14 days after the big race to see ifinfections developed.12(a) What is the name for this experimental design?(b) Use a diagram to outline the design.