Mean Force Analysis of type a curves in Fig. 4 uses the arithmetic mean of the mean peak force and the mean valley force. This should be considered as an average tear force since it gives equal consideration to peak and valley responses. Note that the mean force does not indicate the difference between peak and valley forces. It is possible for two tear curves to have the same mean force when one has a large difference between peaks and valleys, while the other has a small difference between peaks and valleys.