Commonly used rating scales and tests have been found lacking reliability and validity, for example in neurodegenerative diseases studies, owing to not making recourse to the inherent ordinality of human responses, nor acknowledging the separability of person ability and item difficulty parameters according to the well-known Rasch model. Here, we adopt an information theory approach, particularly extending deployment of the classic Brillouin entropy expression when explaining the difficulty of recalling non-verbal sequences in memory tests (i.e., Corsi Block Test and Digit Span Test): a more ordered task, of less entropy, will generally be easier to perform. Construct specification equations (CSEs) as a part of a methodological development, with entropy-based variables dominating, are found experimentally to explain (r =R2 = 0.98) and predict the construct of task difficulty for short-term memory tests using data from the NeuroMET (n = 88) and Gothenburg MCI (n = 257) studies. We propose entropy-based equivalence criteria, whereby different tasks (in the form of items) from different tests can be combined, enabling new memory tests to be formed by choosing a bespoke selection of items, leading to more efficient testing, improved reliability (reduced uncertainties) and validity. This provides opportunities for more practical and accurate measurement in clinical practice, research and trials.

Goal-setting in physiotherapy: exploring a person-centered perspective.

No abstract

Memory ability, together with many other constructs related to disability and quality of life, is of growing interest in the social sciences, psychology and in health care examinations. This chapter will focus on two elements aiming at understanding, predicting, measuring and quality-assuring constructs with examples from memory measurements: (i) explicit methods for testing theories of the measurement mechanism and establishment of metrological standards and (ii) substantive theories explaining the constructs themselves. Building on entropy as a principal explanatory variable, analogous to its use in thermodynamics and information theory, we demonstrate how more fit-for-purpose and valid memory measurements can be enabled. Firstly, memory task difficulty, extracted from a Rasch psychometric analysis of memory measurements of experimental data such as from the European NeuroMET project, can be explained with a construct specification equation (CSE). Based on that understanding, the CSE can facilitate the establishment of objective and scalable units through the generation of novel certified reference “materials” for metrological traceability and comparability. These formulations of CSEs can also guide how best to compose new memory metrics, through a judicious choice of items from various legacy tests guided by entropy-based equivalence, which opens up opportunities for formulating new, less onerous but more sensitive and representative tests. Finally, we propose and demonstrate how to formulate CSEs for person ability, correlated statistically and clinically with sets of biomarkers, that can be a means of providing diagnostic information to enhance clinical decisions and targeted interventions.