Lecture Business statistics in practice (7/e): Chapter 17 - Bowerman, O'Connell, Murphree

Chapter 17 - Process improvement using control charts. After mastering the material in this chapter, you will be able to: Discuss the principles and importance of quality improvement, distinguish between common causes and assignable causes of process variation, sample a process by using rational subgrouping.
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Lecture Business statistics in practice (7/e): Chapter 17 - Bowerman, OConnell, Murphree Chapter17 ProcessImprovementUsingControl ChartsMcGrawHill/Irwin Copyright©2014byTheMcGrawHillCompanies,Inc.Allrightsreserved.ProcessImprovementUsingControlCharts17.1 Quality:MeaningandHistorical Perspective17.2 StatisticalProcessControlandCausesof Variation17.3 SamplingaProcess,Rational SubgroupingandControlCharts17.4 andRCharts 172ProcessImprovementUsingControlChartsContinued17.5 ComparisonofaProcesswith Specifications:CapabilityStudies17.6 ChartsforFractionNonconforming17.7 CauseandEffect,DefectConcentration Diagrams(Optional) 173LO17-1: Discuss theprinciples andimportance of qualityimprovement. 17.1Quality:MeaningandHistorical Perspective Quality ◦Fitnessforuse ◦Extenttowhichcustomerexpectationsaremet Typesofquality ◦Qualityofdesign ◦Qualityofconformance ◦Qualityofperformance 174LO17-1 HistoryoftheQualityMovement 1924 StatisticalQualityControl/ControlCharts, Shewart/BellTelephone 1920’s StatisticalAcceptanceSampling,Bell Telephone 1946 AmericanSocietyforQualityControlcreated 1950 W.EdwardsDemingintroducesstatistical qualitycontrolinJapan 1951 DemingPrizeestablishedinJapan 1980’s TotalQualityManagement(TQM) 1988 MalcolmBaldrigeNationalQualityAwards established 1990’s ISO9000,internationalqualitystandards adopted 175LO17-2: Distinguishbetween common 17.2StatisticalProcessControlandCausescauses and assignablecauses of processvariation. ofProcessVariation Historicalinspectionapproach ◦Inspectionofoutput ◦Actiononoutput  Scrap,rework,downgrade(expensive!) Statisticalprocesscontrol ◦Monitorandstudyprocessvariation ◦Goal:Continuousprocessimprovement ◦Preventingbyqualitythroughprocess improvement 176LO17-2 CausesofProcessVariation Commoncauses ◦Typical(random)variationinherentinprocess design ◦Processinstatisticalcontrol Assignablecauses ◦Unusualprocessvariation ◦Intermittentorpermanentprocesschanges ◦Notcommontoallprocessobservations ◦Processnotinstatisticalcontrol 177LO17-3: Sample aprocess by usingrational subgrouping. 17.3SamplingaProcessandRational SubgroupingandControlCharts Mustdecidewhichprocessvariablestostudy ◦Besttostudyaquantitativevariable  Thismeansweareemployingmeasurementdata Wewilltakeaseriesofsamplesovertime ◦Usuallycalledsubgroups ◦Usuallyofsizetwotosix ◦Usuallyobservedoverashortperiodoftime Wanttoobserveoftenenoughtodetect importantprocesschanges 178LO17-3 ControlCharts Acontrolchartemploysacenterline,upper controllimitandlowercontrollimit Thecenterlinerepresentsaverage performance Theupperandlowercontrollimitsare establishedsothatwhenincontrolalmostall plotpointswillbebetweenthelimits 179LO17-4: Use  and Rcharts to establishprocess control. 17.4andRCharts andRchartsarethemostcommonlyused controlchartsformeasurementdata ◦chartplotssubgroupmeansversustime ◦Rchartplotssubgrouprangeversustime chartmonitorstheprocessmean Rchartmonitorstheamountofvariability Thesetwochartsmustbeusedtogether 1710LO17-5: Detect thepresence of assignablecauses through pattern PatternAnalysisanalysis. Anobservationbeyondthecontrollimits indicatesthepresenceofanassignablecause Othertypesofpatternsalsoindicatethe presenceofanassignablecause Thesepatternsaremoreeasilydescribedin termsofcontrolchartzones ◦A,B,C 1711LO17-6: Decide whethera 17.5ComparisonofaProcesswithprocess i ...