2014 ERP New Member Book

AOACO FFICIAL M ETHODS OF A NALYSIS (2012)

G UIDELINES FOR S TANDARD M ETHOD P ERFORMANCE R EQUIREMENTS Appendix F, p. 7

Table A2. Recommendeddefinitions Bias

Difference between the expectation of the test results and an accepted reference value. Bias is the total systematic error as contrasted to random error. Theremay be one ormore systematic error components contributing to the bias. Ability of theassay to detect target organism in the presence of environmental substances and to be free of cross reaction from environmental substances. Strains or isolates or variants of the target agent(s) that themethodmust not detect. Strains or isolates or variants of the target agent(s) that themethod can detect. Overall fractional response (meanPOD=CPOD) for themethod calculated from the pooled POD j responses of the individual laboratories ( j = 1, 2, ..., L ). a SeeAnnexC . Minimum concentration ormass of analyte in a givenmatrix that can be reported as a quantitative result. Probability of themethod giving a (+) responsewhen the sample is trulywithout analyte. Probability of themethodgiving a (–) responsewhen the sample is trulywithout analyte. Proportionof positive analytical outcomes for a qualitativemethod for a givenmatrix at a given analyte level or concentration. Consult AnnexC for a full explanation. Expected or observed fraction of test portions at a given concentration that gives positive result when tested at a given concentration. Consult Probability of Identification (POI): AStatistical Model for theValidation of QualitativeBotanical IdentificationMethods . c Closeness of agreement between independent test results obtained under stipulated conditions. Themeasure of precision is usually expressed in terms of imprecision and computed as a standard deviation of the test results. d Fraction or percentage of the analyte that is recoveredwhen the test sample is analyzed using the entiremethod . Thereare two types of recovery: ( 1 ) Total recovery basedon recovery of the native plus added analyte, and ( 2 )marginal recovery based only on the addedanalyte (the native analyte is subtracted from both the numerator and denominator). e

Environmental interference

Exclusivity Inclusivity

Laboratory probability of detection (POD)

Limit of quantitation (LOQ)

POD (0) POD (c)

POD

Probability of identification (POI)

Precision (repeatability)

Recovery

Repeatability

Precisionunder repeatability conditions.

Repeatability conditions

Conditionswhere independent test results are obtainedwith the samemethodon identical test items in the same laboratory by the same operator using the same equipment within short intervals of time.

Reproducibility

Precision under reproducibility conditions.

Reproducibility conditions

Conditionswhere independent test results are obtainedwith the samemethodon identical test items in different laboratorieswith different operators using different equipment.

Relative standard deviation (RSD)

RSD= s i

 100/ 

Standard deviation (s i ) –  ) 2 /n] 0.5 a AOAC INTERNATIONALMethodsCommitteeGuidelines for Validation of Biological Threat Agent Methods and/or Procedures ( Calculationof CPOD and dCPODValues fromQualitativeMethodCollaborativeStudyData ), J. AOAC Int . 94 , 1359(2011) and Official Methods of Analysis of AOAC INTERNATIONAL (2012) 19thEd., Appendix I . b International Vocabulary of Metrology (VIM)—Basic and General Concepts and Associated Terms (2008) JCGM 200:2008, Joint Committee for Guides in Metrology (JCGM), www.bipm.org c LaBudde, R.A., &Harnly, J.M. (2012) J. AOAC Int . 95 , 273–285. d ISO 5725-1-1994. e Official Methods of Analysis (2012) AppendixD ( Guidelines for CollaborativeStudyProcedures toValidateCharacteristics of aMethodof Analysis ),AOAC INTERNATIONAL, Gaithersburg, MD. s i = [Σ(x i

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