A dataset with 12 observations on the following 3 variables.

Subject I, II, III, or IV
Drug Caffeine, Placebo, or Theobromine
TapRate Finger taps in a fixed time interval


Scientists Scott and Chen, published research that compared the effects of caffeine with those of theobromine (a similar chemical found in chocolate) and with those of a placebo. Their experiment used four human subjects, and took place over several days. Each day each subject swallowed a tablet containing one of caffeine, theobromine, or the placebo. Two hours later they were timed while tapping a finger in a specified manner (that they had practiced earlier, to control for learning effects). The response is the number of taps in a fixed time interval


The data was found in Statistics in Biology, Vol. 1, by C. I. Bliss (1967), New York: McGraw Hill.


1The original article is "Comparison of the action of 1-ethyl theobromine and caffeine in animals and man," by C. C. Scott and K. K. Chen, Journal of Pharmacological Experimental Therapy, v. 82 (1944), pp 89-97.

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