One factor in the development of tennis elbow, a malady that strikes fear into the hearts of all serious players of that sport, is the impact-induced vibration of the racket-and-arm system at ball contact. It is well known that the likelihood of getting tennis elbow depends on various properties of the racket used. Consider the accompanying scatterplot of x = racket resonance frequency (in hertz) and y = sum of peak-to-peak accelerations (a characteristic of arm vibration, in meters per second per second) for n = 23 different rackets ("Transfer of Tennis Racket Vibrations into the Human Forearm," Medicine and Science in Sports and Exercise [1992]: 1134-1140). Discuss interesting features of the data and of the scatterplot.
