One factor in the development of tennis elbow, a malady that strikes fear in the hearts of all serious tennis players, 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 scatter plot of racket resonance frequency

(Hz) and (a characteristic of arm vibration, in m/sec/sec) for 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 scatter plo