Towards patient-centred cognition metrics

Abstract

Metrological quality assurance is essential if reliable decisions about diagnosis, treatment and rehabilitation are to be made consistently throughout the healthcare system. However, many observations in healthcare are considered to lie 'off the scale' of quantitative measurement. We have previously argued that a fundamental reappraisal of metrology is needed if such ordinal or nominal properties are to be included in an extended quantity calculus on which the SI could be based. As just one example, metrological quality assurance in person-centred care now seems possible in a novel way for partners in care; physician ability (e.g., to diagnose cognitive impairment correctly) and patient ability (e.g., cognitive performance of patients with Alzheimer's disease) using novel formulations of causal Rasch models articulated through construct specification equations (CSEs). Here, as part of our research in the EMPIR NeuroMET 15HLT04 project, we illustrate how construct specification equations and new metrological references for task difficulty for block tests, such as the Knox Cube Test, can be established in terms of entropy, reversals and average distance.