Micronutrients measurement quality assurance program: Helping participants use interlaboratory comparison exercise results to improve their long-term measurement performance

Over the past decade, the Micronutrients Measurement Quality Assurance Program (M(2)QAP) at the National Institute of Standards and Technology (NIST) has administered nearly 40 interlaboratory comparison exercises devoted to fat-soluble vitamin-related analytes in human serum, While M(2)QAP studies have been used to help certify reference materials and to document the performance of analytical systems, the primary focus of the M(2)QAP has been, and remains, the improvement of amongparticipant measurement comparability for target analytes. Recent analysis of historical measurement performance indicated the most efficient mechanism for further improving measurement comparability among participants is the improvement of long-term (months to years) comparability within each laboratory. The summary reports for the M(2)QAP studies are being redesigned to provide more chemist-friendly analyses of participant performance, dissecting systematic and random components of measurement incomparability as functions of analyte level and time. This report documents the semantic and graphical tools developed to help interlaboratory-comparison-exercise participants interpret their own measurement performance.