A Visual Analog Scale (VAS) is a psychometric response scale often used in questionnaires to measure subjective characteristics or attitudes that cannot be directly measured. In the context of epidemiology, VAS is widely utilized to evaluate variables such as pain intensity, health-related quality of life, and treatment satisfaction. The scale is typically a straight line, usually 100 mm in length, with endpoints defining extreme limits such as 'no pain' and 'worst imaginable pain.'
