The Rasch model is not mathematically limited to psychometrics or human respondents; but should also be applicable to more technical agents. This work, as a bridging exercise exploiting this agnostic aspect, explores how psychometric tools can support a major activity in metrology across the disciplines: namely, Interlaboratory Comparisons (ILCs), where one or more common objects are circulated for measurement amongst several laboratories, as a regular tool for assessing performance. ILCs are less developed for ordinal and nominal data and have been rarely studied to date in the human sciences. The present clinical case study examines whether the performance of different surgical interventions—specifically based on carotid artery stenosis outcomes—can be interpreted in terms of metrological ILCs using Rasch psychometric modelling as an alternative to earlier Generalised Linear Mixed Modelling meta-analyses. Particular attention is given to statistical weighting and the definition of a reference value for these qualitative and categorical ILCs. Task difficulty assessed according to Rasch’s principle of specific objectivity provides the ILC reference value for ordinal data. Beyond surgical applications of the present case study, other potential applications include evaluating the performance of in vitro medical devices, large language models, and automated machine-readability for semantic interoperability.