Clinicians depend on reliable laboratory results as they are central to diagnosis, monitoring and risk assessment of patients. These results are then judged against the current evidence base, which arises from previously conducted studies, to assist decision making on future patient care. However, no single study is guaranteed to be both feasible and able to provide valid, informative and relevant answers with optimal precision to all study questions.

The reliability of laboratory results depends heavily on accuracy, understood as a joint index of precision and trueness.¹ Trueness is of particular importance for comparability of results as it allows the use of common reference intervals, treatment strategies and risk assessment tools. The true value is a value consistent with the definition of a given particular quantity obtained by a perfect measurement.² Quantities are measured using procedures with different degrees of complexity. The measurement procedure needed to measure a particular quantity such as the “number of fingers on the hand of a given person” is very simple: counting by direct visual inspection is enough. In contrast, the measurement …