Visual Analog Scales (VAS) are a measurement instrument used to quantify subjective characteristics or attitudes that cannot be directly measured. In epidemiology, VAS are commonly used to assess variables such as pain intensity, quality of life, and overall health status. The scale typically consists of a straight line, usually 10 centimeters in length, with endpoints defining the extreme limits of the variable being measured (e.g., "no pain" to "worst pain imaginable").
