1. 1. Invasive versus Non-Invasive Clinical Measurements in Medicine Clinical measurement has become an essential complement to traditional physical diagnosis. An ideal clinical measurement should be quantitative, have a high level of reliability and accuracy, be safe, acceptable to the patient, easy to perform and non-invasive. The latter demands that the technique should not break the skin or the lining epithelium and should be devoid of effects on the tissues of the body by the dissipation of energy or the introduction of infection 1]. It is therefore logical that for a given measurement,...