The Mokken scale: A critical discussion

Abstract

The Mokken scale is critically discussed. It is argued that Loevinger’s H, adapted by Mokken and advocated as a coefficient of scalability, is sensitive to properties of the item set which are extraneous to Mokken’s requirement of holomorphy of item response curves. Therefore, when defined in terms of H, the Mokken scale is ambiguous. It is furthermore argued that item-selection free statistical inferences concerning the latent person order appear to be insufficiently based on double monotony alone, and that the Rasch model is the only item response model fulfilling this requirement. Finally, it is contended that the Mokken scale is an unfruitful compromise between the requirements of a Guttman scale and the requirements of classical test theory.