Visual analogue scales [letter]

Is Dr Maxwell starting from the wrong premise?His thought provoking study (Maxwell, 1978) raises the question whether the relationship of the visual analogue scale scores to the actual sound volumes is relevant to clinical trial work, in which the aim of selfrating scales is to quantify patients' own sensations.In most clinical situations, symptoms such as pain, nausea, depression, anxiety, etc. are being evaluated, thus questions of the 'correctness' of the responses would not be applicable.On a matter of practical detail, the description of the sound source does not make it clear whether the 'slide rule' calibration was in fact on a linear scale in decibels.