Designation:E2489−11AnAmericanNationalStandardStandardPracticeforStatisticalAnalysisofOne-SampleandTwo-SampleInterlaboratoryProficiencyTestingPrograms1ThisstandardisissuedunderthefixeddesignationE2489;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thispracticedescribesmethodsforthestatisticalanaly-sisoflaboratoryresultsobtainedfrominterlaboratoryprofi-ciencytestingprograms.AsinaccordancewithPracticeE1301,proficiencytestingistheuseofinterlaboratorycom-parisonsforthedeterminationoflaboratorytestingormea-surementperformance.Conversely,collaborativestudy(orcollaborativetrial)istheuseofinterlaboratorycomparisonsforthedeterminationoftheperformancecharacteristicsofamethod,ascoveredbyPracticeE691.1.1.1MethodAcoverstestingprogramsusingsingletestresultsobtainedbytestingasinglesample(eachlaboratorysubmitsasingletestresult).1.1.2MethodBcoverstestingprogramsusingpairedtestresultsobtainedbytestingtwosamples(eachlaboratorysubmitsonetestresultforeachofthetwosamples).Thetwosamplesshouldbeofthesamematerialortwomaterialssimilarenoughtohaveapproximatelythesamedegreeofvariationintestresults.1.2MethodsAandBareapplicabletoproficiencytestingprogramscontainingaminimumof10participatinglaborato-ries.1.3Themethodsprovidedirectionforassessingandcatego-rizingtheperformanceofindividuallaboratoriesbasedontherelativelikelihoodofoccurrenceoftheirtestresults,andfordeterminingestimatesoftestingvariationassociatedwithrepeatabilityandreproducibility.Assumptionsarethatama-jorityoftheparticipatinglaboratoriesexecutethetestmethodproperlyandthatsamplesareofsufficienthomogeneitythatthetestingresultsrepresentresultsobtainedfromeachlaboratorytestingessentiallythesamematerial.Eachlaboratoryreceivesthesameinstructionsorprotocol.1.4Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifan...
