Visual estimation
The person, for example, is told that the one end of the line is 'no pain at all' and at the other end is 'unbearable pain' and then they indicate on the line where they think there pain fits.
A visual analogue scale is a system to rate a person's level of a particular symptom along a line drawn between two fixed points.
The person, for example, is told that the one end of the line is 'no pain at all' and at the other end is 'unbearable pain' and then they indicate on the line where they think there pain fits.