Dr. Jones is interested in marketing his Super-Strength Energy Drink and believes that the caffeine in his super-strength energy drink will lead to better performance on exams. He studied 300 college students who had similar grades. He randomly divided the participants into two groups. Dr. Jones had his research assistants give half of the students a decaf placebo drink, and the other half got his fully caffeinated Super-Strength Red Bull. Participants were not told which beverage they were given, and the research assistants did not know which beverage was in each cup. He gave the entire group the same final exam and found that the caffeine group performed significantly better on the exam