Sample sizes needed for specified margins of relative error in the estimates of the repeatability and reproducibility standard deviations.
Sample size formulas are developed to estimate the repeatability and reproducibility standard deviations (Sr and S(R)) such that the actual error in (Sr and S(R)) relative to their respective true values, sigmar and sigmaR, are at predefined levels. The statistical consequences associated with AOAC INTERNATIONAL required sample size to validate an analytical method are discussed. In addition, formulas to estimate the uncertainties of (Sr and S(R)) were derived and are provided as supporting documentation. Formula for the Number of Replicates Required for a Specified Margin of Relative Error in the Estimate of the Repeatability Standard Deviation.
McClure
Foster D
FD
U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Scientific Analysis and Support, Division of Mathematics, 5100 Paint Branch Pkwy, College Park, MD 20740-3835, USA. foster.mcclure@cfsan.fda.gov
Lee
Jung K
JK
D002623:Chemistry Techniques, Analytical / Q000379:methods*; D015233:Models, Statistical; D015203:Reproducibility of Results; D018401:Sample Size; D035501:Uncertainty