274 Chapter 6 Neural Networks
stepped up and down steps of various heights. The response variable,
heart rate, was measured in beats per minute. There were two different
step heights: 5.75 inches (coded as 0) and 11.5 inches (coded as 1). There
were three rates of stepping: 14 steps/min (coded as 0), 21 steps/min
(coded as 1), and 28 steps/min (coded as 2). This resulted in six possible
height/frequency combinations. Each subject performed the activity for
three minutes. Subjects were kept on pace by the beat of an electric met-
ronome. One experimenter counted the subject’s pulse for 20 seconds
before and after each trial. The subject always rested between trials until
her or his heart rate returned to close to the beginning rate. Another ...