In 1959, Ragnar Frisch prompted Georg Rasch to formalise a separability theorem that continues today to serve as the basis of a wide range of theoretical and applied developments in psychological and social measurement. Previously unnoted are the influences on Rasch exerted by Frisch’s...

Rasch’s unidimensional models for measurement show how to connect object measures (e.g., reader abilities), measurement mechanisms (e.g., machine-generated cloze reading items), and observational outcomes (e.g., counts correct on reading instruments). Substantive theory shows what...

In 1979, the Danish mathematician Georg Rasch recounted a 1959 visit with his former teacher, and later economics Nobel Prize winner, Ragnar Frisch. At this time, Frisch prompted Rasch to formalize his work in a separability theorem. Previously unnoted is that Frisch's close colleague, Irving...

Measurement quality is a fundamental factor in determining the cost of transactions within organizations and markets. A huge gulf separates the meaningfulness and precision of business metrics as currently achieved from the quality that has been routinely obtained for decades in research and in...