Is caff eine dependence real Many people start their day

Chapter 6, Problem 6.51

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Is caff eine dependence real? Many people start their day with a jolt of caff eine from coff ee or a soft drink. Most experts agree that people who take in large amounts of caff eine each day may suff er from physical withdrawal symptoms if they stop ingesting their usual amounts of caff eine. Researchers recruited 11 volunteers who were caff eine dependent and who were willing to take part in a caff eine withdrawal experiment. Th e experiment was conducted on two 2-day periods that occurred one week apart. During one of the 2-day periods, each subject was given a capsule containing the amount of caff eine normally ingested by that subject in one day. During the other study period, the subjects were given placebos. Th e order in which each subject received the two types of capsules was randomized. Th e subjects diets were restricted during each of the study periods. At the end of each 2-day study period, subjects were evaluated using a tapping task in which they were instructed to press a button 200 times as fast as they could.26 (a) Carefully describe the design of this experiment. How was blocking incorporated, and why? (b) Why did researchers randomize the order in which subjects received the two treatments? (c) Could this experiment have been carried out in a double-blind manner? Explain