The impact of qualitative analysis in laboratory medicine

Laboratory medicine is a challenge for the metrologically and terminologically inclined scientist. One main reason is the need for a sound theory that can be applied in a systematic way to cover all aspects of examinations, i.e., those procedures whose results are reported on an ordinal scale and those reported on more primitive scales (e.g., classifications and narratives). Validation of procedures for examinations involving properties on a nominal scale is especially difficult to achieve because it is hard to find gold standards, in the conventional sense, against which to validate and which combine performance characteristics and clinically relevant specificity and sensitivity. We present a systematic, unambiguously defined terminology (the C-NPU coding scheme) for metrologically derived terms for expressing properties, and present some examples of how to attain diagnostic goals. If the analytic process in the laboratory can be subsumed into medical contexts in a systematic way, many pitfalls in reporting results can be avoided.