Here's a question about "Westgard Rules" that we get a LOT: "Does the violation of the 10x rule mean anything? Can we ignore it?" At the heart of this question is another, deeper question: what QC rules are actually necessary to assure the quality of a method? With the help of user-submitted data on a phosphorus method, we'll take a closer look at this question.
Stockl et al's landmark paper on vitamin D establishes desirable specifications for imprecision and inaccuracy (trueness). But what about total allowable error? With the use of QC Design tools, we can turn individual specifications into a broader quality requirement.