The Visual Analog Scale (VAS) is a psychometric response scale used in questionnaires to measure subjective characteristics or attitudes that cannot be directly measured. In the context of epidemiology, it is often utilized to assess the intensity of symptoms, such as pain, fatigue, or other health-related quality of life parameters. The VAS typically consists of a horizontal line, usually 100 mm in length, anchored by two verbal descriptors, for example, "no pain" and "worst pain imaginable."
