The connection between magnitude and discrimination scales and direct and indirect scaling methods

(1) An analysis of the method of paired comparisons shows that Case V and Case VI, the latter characterized by log-normal distributions and Weber's law for subjective continua, are fundamentally indistinguishable. Case VI produces a log-arithmetic interval scale of subjective magnitude. (2) It is demonstrated that the difference between discrimination scales according to Case V and from category rating is due to the difference between intra- and interindividual variability yielding different Weber functions.This research was supported by the Humanistic Faculty of the University of Stockholm and by the Swedish Social Science Research Council. I am indebted to Mr. U. Forsberg for computational assistance.