A few years later in 1974, Westgard Select QC samples.
Select QC samples with analyte levels that monitor clinical decision points Verify that QC samples react the same way as patient samples (i.e.
The ideal control material will: "The appropriateness of an optimal QC strategy seems very much to depend on the quality required, as well as the expected instability of the analytical method (e.g., type, magnitude and frequency of errors)." [Wandrup ]  "The act of establishing your own means and SDs brings in the performance specifications observed in your own laboratory." [Carey]  “A laboratory metric that has been used to select and design QC procedures is the critical systematic error, SEc, which can be calculated from the tolerance or quality requirement defined for the test and the imprecision and inaccuracy observed for the method […] The implication is that the error detection capability of the QC procedure should complement the performance capability of the process.
With high process capability, the errors that cause defective results will be large and more easily detected by statistical quality control.
Additionally, it centers on satisfaction of customer’s needs by the provision of valuable services and products.
The third core value is defect deterrence and nonconformity.
changes in accuracy or precision of patient results are reflected by proportional changes in accuracy or precision in QC sample results) Select a QC strategy consisting of frequency of testing, QC rules and processes to create and examine QC charts.
Choose a QC strategy that will always detect changes that would cause any results to fail to meet the defined performance standard.
Now we are giving you, the reader, the opportunity to rate your own QC practice and to help prove or disprove that gap.
If the QC theories generally recommended by recognized QC experts are indeed the right way to perform laboratory quality control, the consequences of a significant gap between their theories and the typical laboratory practice pose potentially life-threatening consequences for patients.