Premium
A Properly Developed Consensus from a Proficiency Test is, for All Practical Purposes, Interchangeable with a Certified Value for a Matrix Reference Material Derived from an Interlaboratory Comparison
Author(s) -
Thompson Michael
Publication year - 2018
Publication title -
geostandards and geoanalytical research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.037
H-Index - 73
eISSN - 1751-908X
pISSN - 1639-4488
DOI - 10.1111/ggr.12195
Subject(s) - certification , traceability , round robin test , computer science , term (time) , test (biology) , stability (learning theory) , measurement uncertainty , certified reference materials , foundation (evidence) , value (mathematics) , matrix (chemical analysis) , statistics , mathematics , law , machine learning , political science , materials science , paleontology , physics , quantum mechanics , detection limit , composite material , biology
A properly developed consensus from a proficiency test is, for all practical purposes, interchangeable with a certified value derived from an interlaboratory comparison. But some scientists have doubts about the metrological status of such values. In particular, the materials are not regarded as equivalent to certified reference materials (CRM) because of a lack of traceability of the consensus value. However, the detailed considerations in this study show that such a distinction is without foundation. The following issues are addressed. (a) Misgivings about the traceability of an interlaboratory consensus are found to be insubstantial because chemical measurements are hardly ever fully traceable. (b) Reproducibility (i.e., interlaboratory) conditions account for all sources of variation in results other than long‐term stability, so lead to a valid estimate of uncertainty. (c) Certification of a reference material according to ISO procedures is homologous with a proficiency test and no more secure against bias in the characterised value and its standard error. In particular, residual (common) bias cannot be fully addressed in either approach. (d) A consensus in itself attests to a valid outcome. (e) Proficiency test providers have access to a powerful method of monitoring long‐term stability that is denied to CRM producers.