Uncertainty of measurement in the clinical laboratory service

Measurement uncertainty in the context of clinical laboratories is inextricably linked to imprecision, and therefore the assessment of this poorly understood factor is an increasing element of the accreditation process. In view of the need to provide some clarity, Pathology in Practice is running a series of articles written by Stephen MacDonald.

The first of these articles appeared in the February issue (page 13) and focused on definition of the measurand. In the next issue, the focus will shift to assay modelling and characterising the measurement, a process which identifies and categorises uncertainty sources, collects the data available, and uses those data to describe and quantify the uncertainty.

Subsequent articles in this important series aim to cover development of the model of the measurement; techniques for calculation of the standard uncertainty; combination of standard uncertainties; sensitivity coefficients and the uncertainty index; coverage factor and the expanded uncertainty; and, reporting the uncertainty budget and use moving forward.

Once complete, this compendium of vital information will chart a sensible progression for the application of measurement uncertainty in pathology laboratories, and will be a helpful resource for the process from beginning to end.