Analogskala

An analog scale, or analogskala, is a measurement method that represents a continuous spectrum of values rather than distinct categories. It is used to quantify subjective experiences such as pain, fatigue, mood, or perceived stimulus intensity. The central idea is that respondents indicate a position along a line or space that corresponds to the strength or magnitude of the experience.

The most widely used form is the visual analog scale (VAS). It typically consists of a straight line, commonly 10 centimeters long, with endpoints labeled (for example, "no pain" and "worst imaginable pain"). Respondents place a mark on the line, and the position is translated into a continuous numerical value, often in millimeters.

Other variants include the numeric rating scale (NRS), where respondents choose a number on a continuous range, and verbal analog scales, which use descriptors along a continuum. Although called continuous, in practice data from analog scales are analyzed as interval data in many studies. The scales may be oriented horizontally or vertically and tailored to the domain.

Administration requires clear instructions to minimize bias, a stable measurement setup, and a calibrated means of reading marks. Reliability relies on respondent understanding and consistent interpretation, while validity depends on the scale's ability to capture the intended construct.

Advantages of analog scales include high sensitivity to small changes and straightforward administration. Limitations include potential subjective interpretation, variability between respondents, and challenges for individuals with limited literacy or motor ability. They are common in clinical research and psychology for tracking pain, mood, or perceived effort.

See also: Visual analog scale; continuous scale; Likert scale; measurement theory.