title: NIST micronutrients measurement quality assurance program: characterizing individual participant measurement performance over time.
abstract: The mission of the Micronutrients Measurement Quality Assurance Program (M2QAP) at the National Institute of Standards and Technology is enhanced interlaboratory measurement comparability for fat-soluble vitamin-related measurands in human serum. We recently described improved tools for evaluating individual participant measurement performance in single interlaboratory comparison exercises; we here apply and extend these tools to the evaluation of participant performance over the entire 15-year history of the M2QAP. We describe and illustrate a set of interconnected graphical reporting tools for identifying long-term trends and single-exercise events. We document and discuss recurrent patterns we observe in the measurement performance characteristics for M2QAP participants. The graphical analysis techniques utilized may be applicable to other interlaboratory comparison programs.
authors.affiliation: Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA. david.duewer@nist.gov
authors.forename: D L
authors.initials: DL
authors.lastname: Duewer
authors.forename: M C
authors.initials: MC
authors.lastname: Kline
authors.forename: K E
authors.initials: KE
authors.lastname: Sharpless
authors.forename: J B
authors.initials: JB
authors.lastname: Thomas
authors.forename: M
authors.initials: M
authors.lastname: Stacewicz-Sapuntzakis
authors.forename: A L
authors.initials: AL
authors.lastname: Sowell
mesh_terms: D006801:Humans; D009313:National Health Programs; D011786:Quality Control; D015203:Reproducibility of Results; D014212:Tretinoin / Q000097:blood*; D014481:United States; D014810:Vitamin E / Q000097:blood*; D019207:beta Carotene / Q000097:blood*
chemical_list: D019207:beta Carotene; D014810:Vitamin E; D014212:Tretinoin