Refer to Exercise 5 for a description of a study about caffeine.
Exercise 5
In a double-blind study, researchers tested whether small doses of caffeine would improve highly trained male cyclists’ times in a hot environment (95°F, 25% humidity). The individuals were 9 highly trained male cyclists who rode a stationary bicycle in a hot climate chamber on three separate occasions. The first session was a familiarization session. On the second session, some athletes took a caffeine pill and the rest took a placebo pill of Metamucil. On the third session, each athlete took the other pill. For each of the second and third sessions, the cyclists were randomly assigned to the treatment and control groups. The study concluded that a small dose of caffeine improves a highly trained male cyclist’s time in a hot environment.
a. Why was the placebo a Metamucil pill rather than a sugar pill?
b. What does it mean that the study is double-blind? How could that 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. The cyclists were instructed to avoid caffeine for at least 12 hours prior to each session. The half-life of caffeine in the bloodstream is 6 hours, which means that caffeine will be cut in half every 6 hours. Drinking 4 cups of coffee 12 hours before the trial would be equivalent to drinking how much coffee at the start of the session? Would that be a problem? Explain.