Standard systems: the foundational element of measurement theory

All measurement involves some system or mechanism for deriving metric information and yet definitions and theories of the process in psychology have not emphasized this element. The theory of standard systems, on the other hand, introduces the system as the foundational element in the measurement process. When combined with a categorization of types of standard systems and other elements of the measurement process, the theory highlights, and provides a meta-theoretical framework for integrating the historically important and heuristic contributions to measurement theory. The early positive contributions that focussed on the development of systems of measurement and models for deriving metric information, were deflected by the requirements outlined in the physical addition theory, and in the limiting theory of scales. Some of these requirements were liberalized by subsequent theoretical thrusts. Future research should bolster the promise of the Rasch solutions with emphasis on the provision of standard systems with empirically anchored magnitude points.