“If you cannot measure it, you cannot improve it,” a phrase generally attributed to Lord Kelvin (William Thomson, 1824-1907), is a timely admonition for today’s medicine and clinical trials. In today’s world, we can measure countless things. Thus, Kelvin’s advice now applies to the need to measure the right things, under the right circumstances, to improve “it.” “It” presumably, is health, or the subject’s current condition, or more topically, his/her quality of life.