SCALING OF RATINGS - CONCEPTS AND METHODS

Rating scales provide an efficient and widely used means of recording judgments. This paper reviews scaling issues within the context of a psychometric model of the rating process and describes several methods of scaling rating data. The scaling procedures include the simple mean, standardized values, scale values based on Thurstone's Law of Categorical Judgment, and regression-based values. The scaling methods are compared in terms of the assumptions they require about the rating process and the information they provide about the underlying psychological dimension being assessed.