The problem has been that digital palpation is rather subjective and not a very reliable measure for the purpose of documentation. This problem has been solved by using a simple compressive-force gauge fitted with a soft rubber tip implement. Plenty of published papers are available to support its use. Use of the pressure algometer, as described above, is actually measuring pain threshold as opposed to pain tolerance. Pain threshold is the point where a sensation like firm pressure begins to feel unpleasant and painful.
Pain tolerance is the point where a painful stimulus can no longer be tolerated.
This distinction is important in algometry. To answer this question, I used my algometer on 10 patient. Each patient selected had complaints of pain between the shoulder blades. With palpation I determined that the T-5 vertebra was subluxated. They had an average pre-adjustment pressure threshold of 3.2 kilograms.