ForewordIntroductionScopeNormative referencesTerms and definitionsBasic conceptsGeneralCharacterizationVerificationMethod comparisonSamplesSpecifications: some guideline valuesDesigns for determining performance characteristics of a methodGeneral considerationsDetermination of sensitivity, specificity, efficiency, selectivity, false positive rate and false negative rateType of samples to be usedNumber of samplesProcedureCategorical performance characteristicsWorked exampleDetermination of the upper limit and consideration of the lower limit of detectionWorking rangeUpper limit related to linearityType and number of samples to be usedWorked examplePreparationGeneral proportionality testInterpretation of data and further stepsThe lower limit of detectionAssessment of precision: Determination of repeatability and reproducibilityGeneralRepeatabilityDesignWorked example: Tabulation of countsWorked example: Detection of over-dispersion by applying the Poisson index of dispersionIntralaboratory reproducibilityDesignWorked example for colony countsWorked example for MPN systemsRobustnessGeneralExperimental designs for effects due to time and temperatureRelative recoveryGeneralDetermination of relative recoveryUncertainty of countingGeneralExperimental design for assessing the uncertainty of counting coloniesExample of individual (or personal) uncertainty of counting coloniesExample of intralaboratory uncertainty of counting coloniesExample of intralaboratory uncertainty of reading MPNDesigns for single laboratory verification of a methodGeneral considerationsCalculation of sensitivity, specificity, efficiency, selectivity, false positive rate and false negative rateType of sample to be usedNumber of samplesProcedure for confirmationCategorical performance characteristicsDetermination of repeatabilityUncertainty of countingProcedure for single laboratory verificationMathematical models of variation (informative)GeneralIntrinsic precision of colony countsIntrinsic precision of MPN countsGeneralSingle dilution MPNMultiple dilution MPN“Exact” precisionApproximate characteristic precisionOver-dispersionGeneralThe negative binomial modelDetection of over-dispersionQuantifying over-dispersionAnscombe’s method IRegression approachIndex of dispersion (χ or G) approachOver‑dispersion at detector levelAssessment of the lower limits (normative)GeneralDetection level based on probabilityPoisson modelMPN methodsNegative binomial model of over‑dispersionLimit of determination based on precisionGeneralThe Poisson modelThe negative binomial modelDesign detection levelsAssessment of the upper limit (normative)GeneralStatistical evaluation of the upper limitDetermination of the operational variability in repeatability and intralaboratory reproducibility conditions (normative)General case: Statistical evaluation in a repeatability experimentGeneral case: Statistical evaluation in an intralaboratory reproducibility experiment for colony count methodGeneral case: Statistical evaluation in an intralaboratory reproducibility experiment for MPN methodsUncertainty of counting (normative)GeneralStatistical determination of the uncertainty of counting colonies and reading MPNIndividual (or personal) uncertainty of counting coloniesIntralaboratory uncertainty of counting coloniesDetermination of the operational variability (interlaboratory reproducibility) in a collaborative performance study (normative)Requirement for an interlaboratory precision experimentGeneral case for colony count methods – statistical evaluation for a given set of samplesCalculation approachDetermination of the individual and overall repeatability for the laboratoriesDetermination of the interlaboratory component of variabilityDetermination of the values of 0,2 and 0,2Worked example for colony count methodGeneralDetermination of the individual and overall dispersions in repeatability conditionsDetermination of the interlaboratory dispersion in reproducibility conditionsFinal expression of the interlaboratory precision parameters of the methodWorked example for a MPN methodGlossary of principal symbols (informative)Bibliography