Abstract
The consistent description and treatment of metrological data in laboratory medicine are hampered by the lack of a systematic, universally accepted nomenclature and by variations in the conceptual understanding of uncertainty. The differences between the classical approach to a result as consisting of a true value plus errors and the new approach of a measured corrected value with uncertainty based on a detailed uncertainty budget are discussed. The various definitions of some relevant concepts, including ?accuracy?, the new concept ?trueness?, and ?precision?, are contrasted, and proposed modifications are presented.