MAIMON RESEARCH LLC: RECONSTRUCTING HEALTH
TECHNOLOGY ASSESSMENT

UNDERSTANDING THE AXIOMS OF REPRESENTATIONAL MEASUREMENT

MEASUREMENT IN HTA

Health technology assessment, like every scientific discipline, depends upon measurement.
Claims regarding therapy impact, patient outcomes, resource utilization and quality of life can
only be meaningful if they are supported by measures that satisfy accepted scientific standards.
The purpose of this website is to explore the role of measurement in HTA and to examine the
implications of applying the scales of measurement and the axioms of representational
measurement to contemporary therapy assessment.

For more than four decades HTA has been dominated by utilities, QALYs, reference-case
simulation models and cost-effectiveness claims. These approaches have become embedded in
reimbursement decisions, academic research and professional education throughout the world.
Yet a fundamental question is seldom asked: do the entities entering these frameworks possess
the measurement properties necessary to support the arithmetic operations imposed upon them?
Before arithmetic can be undertaken, measurement must first be established. This principle is
accepted throughout quantitative science and forms the starting point for the analyses presented
here.

The material on this site draws upon large language model interrogations of agencies, academic
research centres, journals, professional organizations and educational institutions across multiple
countries. These interrogations provide a unique opportunity to examine how measurement
concepts are represented within the HTA knowledge base. Particular attention is given to the
principles of representational measurement, the distinction between manifest and latent
attributes, the role of ratio measurement and the contribution of Rasch measurement to the
assessment of subjective outcomes.

A consistent theme emerges. Across a wide range of institutions, numerical constructs are often
accepted without careful consideration of their measurement status. The consequence is what has
been described as measurement inversion, where arithmetic precedes measurement rather than
measurement governing arithmetic. Understanding the implications of this reversal is central to
understanding the strengths and limitations of contemporary HTA.

The purpose of this website is therefore twofold. First, it examines the place of measurement
within current HTA practice in the United States, United Kingdom and internationally. Second, it
considers how HTA might be reconstructed around lawful measurement, empirical evaluation
and falsification. The proposed framework recognizes two lawful forms of measurement for
therapy assessment: linear ratio measures for manifest attributes and Rasch logit ratio measures
for latent attributes. Together these provide a foundation for a new generation of evaluable,
replicable and scientifically credible claims regarding therapy impact.