Psychometric methods: the need for new conceptual advances

There are many unresolved issues concerning both the conceptual and practical aspects of measurement in the field of psychology. This situation persists despite its long-standing and fundamental role in the activities of the majority of psychologists and despite intense scientific enquiry. These issues concern, essentially, the role of qualitative variables, the neglect of non-linear relationships, inadequate sample size, and the difficulties in accounting for the behaviour of intrinsically complex systems, like those studied by psychology. This paper is devoted to briefly review these issues and to discuss the possible effects resulting from generalizations of traditional measurement tools, used by psychologists, related to the introduction of further conceptual approaches borrowed from other scientific disciplines. Recourse to the latter seems related to shortcomings in measurement approaches used in psychometrics, which heavily influence the choice of method used to estimate uncertainty in psychological measurement.