AOAC GFA Stakeholder Program Meeting Book (March 15, 2023)

3.22 Repeatability Variation arising when all efforts are made to keep conditions constant by using the same instrument and operator (in the same laboratory) and repeating during a short time period. Expressed as the repeatability standard deviation (SDr); or % repeatability relative standard deviation (%RSDr). 3.23 Reproducibility Variation arising when identical test materials are analyzed in different laboratories by different operators on different instruments. The standard deviation or relative standard deviation calculated from among-laboratory data. Expressed as the reproducibility standard deviation (SDR); or % reproducibility relative standard deviation (%RSDR). (ISO 5725-1:1994) “Repeatability” and “Reproducibility” should remove the references to standard deviations, in the spirit of not wanting to add statistics into the parameter definitions. This is especially important here for qualitative methods – the statistics may be different than those used in ISO 5725, which is strictly about quantitative method validation. Consider removing ISO reference. ISO House Style: Statistical symbols The statistical terms and their symbols are defined in the ISO 3534 series. Use the term “coefficient of variation” with the symbol CV, not “relative standard deviation” (RSD), which is the deprecated term. EXAMPLES Can we use RSDr instead of %RSDr? it is a duplication

coefficient of variation, repeatability: CV,r coefficient of variation, reproducibility: CV,R