Designation:G166−00(Reapproved2011)StandardGuideforStatisticalAnalysisofServiceLifeData1ThisstandardisissuedunderthefixeddesignationG166;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thisguidepresentsbrieflysomegenerallyacceptedmethodsofstatisticalanalyseswhichareusefulintheinter-pretationofservicelifedata.Itisintendedtoproduceacommonterminologyaswellasdevelopingacommonmeth-odologyandquantitativeexpressionsrelatingtoservicelifeestimation.1.2Thisguidedoesnotcoverdetailedderivations,orspecialcases,butrathercoversarangeofapproacheswhichhavefoundapplicationinservicelifedataanalyses.1.3Onlythosestatisticalmethodsthathavefoundwideacceptanceinservicelifedataanalyseshavebeenconsideredinthisguide.1.4TheWeibulllifedistributionmodelisemphasizedinthisguideandexamplecalculationsofsituationscommonlyen-counteredinanalysisofservicelifedataarecoveredindetail.1.5Thechoiceanduseofaparticularlifedistributionmodelshouldbebasedprimarilyonhowwellitfitsthedataandwhetheritleadstoreasonableprojectionswhenextrapolatingbeyondtherangeofdata.Furtherjustificationforselectingamodelshouldbebasedontheoreticalconsiderations.2.ReferencedDocuments2.1ASTMStandards:2G169GuideforApplicationofBasicStatisticalMethodstoWeatheringTests3.Terminology3.1Definitions:3.1.1materialproperty—customarily,servicelifeisconsid-eredtobetheperiodoftimeduringwhichasystemmeetscriticalspecifications.Correctmeasurementsareessentialtoproducingmeaningfulandaccurateservicelifeestimates.3.1.1.1Discussion—ThereexistsmanyASTMrecognizedandstandardizedmeasurementproceduresfordeterminingmaterialproperties.Asthesepracticeshavebeendevelopedwithincommitteeswithappropriateexpertise,nofurtherelabo-rationwillbeprovided.3.1.2beginningoflife—thisisusuallydeterminedtobethetimeofmanufacture.Exceptionsmayincludetimeofdeliv...
