Designation:D3244−12AnAmericanNationalStandardStandardPracticeforUtilizationofTestDatatoDetermineConformancewithSpecifications1ThisstandardisissuedunderthefixeddesignationD3244;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.INTRODUCTIONThepropertiesofcommercialpetroleumproductsaremeasuredbystandardizedlaboratorytestmethodstochecktheirconformancetospecifications.Twoormoremeasurementsofthesamepropertyofaspecificsamplebyanygiventestmethodusuallywillnotgivepreciselythesameanswer.Therefore,thetestmethodsgenerallyincludeaparagraphontheprecisionofresults.Thisprecisionisanexpressionofthereliabilityofthevalueofthemeasuredproperty.Manydifficultiesthatariseininterpretingspecificationsareduetotestimprecision.Becauseofthis,atruevalueofapropertycanneverbedeterminedexactly;anditisnecessarytoinferfrommeasuredvaluestherangewithinwhichthe“truevalue”islikelytolie.Themainpurposeofthispracticeistoindicatehowtestimprecisionshouldbeinterpretedrelativetospecificationvalues.1.Scope*1.1Thispracticecoversguidelinesandstatisticalmethod-ologieswithwhichtwoparties,usuallyasupplierandareceiver,cancompareandcombineindependentlyobtainedtestresultstoobtainanAssignedTestValue(ATV)forthepurposeofresolvingaproductqualitydispute.1.2ThispracticedefinesatechniqueforcomparinganATVwithaspecificationlimit.1.3Thispracticeappliesonlytothosetestmethodswhichspecificallystatethattherepeatabilityandreproducibilityvaluesconformtothedefinitionsherein.1.4ThestatisticalprinciplesandmethodologyoutlinedinthispracticecanalsobeusedtoobtainanATVforspecificationconformancedecisionwhenmultipleresultsareobtainedforthesamebatchofproductwithinasinglelaboratory.Forthisapplication,siteprecision(R’)asdefinedinPracticeD6299shallbeusedinlieuoftestmethodpublishedreproducibility(R).2.ReferencedDocuments2.1ASTMStandards:2D...
