Designation:D3244−21aAnAmericanNationalStandardStandardPracticeforUtilizationofTestDatatoDetermineConformancewithSpecifications1ThisstandardisissuedunderthefixeddesignationD3244;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.INTRODUCTIONThepropertiesofcommercialpetroleumproductsaremeasuredbystandardizedlaboratorytestmethodstoassesstheirconformancetospecifications.Twoormoremeasurementresultsobtainedbyperformingthesametestmethodforthesamepropertyofaspecificsampleusuallywillnotbenumericallyidentical.Therefore,thetestmethodsgenerallyincludeaparagraphontheprecisionofresults.Thisprecision(or,amoreappropriatetermisimprecision)isanexpressionofthedegreeofagreementthatcanbeexpectedbetweentheaforementionedmeasurements.Manydifficultiesthatariseinassessingconformancetospecificationsareduetotestimprecision.Becauseofthis,atruevalueofapropertycanneverbedeterminedexactly;anditisnecessarytoinferfrommeasuredvaluestherangewithinwhichthe“truevalue”islikelytolie.Themainpurposeofthispracticeistoindicatehowtestimprecisionshouldbeinterpretedrelativetospecificationlimitvalues.1.Scope*1.1Thispracticecoversguidelinesandstatisticalmethod-ologieswithwhichtwoparties(seeNote1)cancompareandcombineindependentlyobtainedtestresultstoobtainanAssignedTestValue(ATV)forthepurposeofresolvingadisputeoverproductpropertyconformancewithspecification.NOTE1—Applicationofthispracticeisusually,butnotlimitedto,betweensupplierandreceiverofaproduct.1.2ThispracticedefinesatechniqueforestablishinganAcceptanceLimit(AL)andAssignedTestValue(ATV)toresolvethedisputeoverapropertyconformancewithspecifi-cationbycomparingtheATVtotheAL.1.3Thispracticeappliesonlytothosetestmethodswhichspecificallystatethattherepeatabilityandreproducibilityvaluesconformtothedefinitionsherein.1.4Thestatisticalprinciplesandmethodologyou...
