title: Computation of HORRAT values.
abstract: The formula for the Horwitz ratio (HORRAT) as presented in the Study Director's Manual of AOAC INTERNATIONAL is applicable only when the concentration is in the unit/unit form (e.g., microg/microg, g/g, etc.). When the analyte concentration is a trace or mass fraction amount (e.g., microg/g), the formula generates incorrect HORRAT values. Alternative calculation procedures are presented to circumvent such problems.
authors: 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. fmcclure@cfsan.fda.gov
authors: Foster D
authors: FD
authors: McClure
authors: Jung-Keun
authors: JK
authors: Lee
mesh_terms: D005504:Food Analysis / Q000592:standards / Q000706:statistics & numerical data*; D008433:Mathematics; D008832:Microchemistry; D015203:Reproducibility of Results