水晶球软件使用Crystal Ball.ppt

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1、ProjectManagementSession9CrystalBallOPIM52701Session9GoalsUnderstandwhyriskmustbeanalyzedKnowpros/consforthreewaystoanalyzeriskIdentifyrandomvariablesinmodelsKnowthefourstepsofasimulationprocessGeneraterandomnumberswithCrystalBallUsethefourstepsofasimulationprocessExplainhowCrystalBa

2、llsupportsProj.Mgmt.2Mostreal-worldbusinesssituationstodayareprobabilistic,butthedecisionmodelsusedtodealwiththemaredeterministic.Howtodealwithrandomness?IgnoreitSimplifyproblemtomakeitanalyticallytractable,getsolution,thenignorereal-lifecomplicationsFindawaytoobtainanapproximatesoluti

3、ontoreal-worldproblems3DealingwithRandomnessMonteCarlosimulationisamethodbywhichapproximatesolutionsareobtainedtorealistic(andthereforecomplicated)problemsThisisincontrasttoanalyticalmethods,whichobtainexactsolutionstohighlystylizedproblemsTradeoffbetweenrigorandrelevance4MonteCarloSim

4、ulationWhatisthis?Y=f(X1,X2,…,Xk)Often,thevaluesforoneormore"input"cellsareunknownoruncertainThiscreatesuncertaintyaboutthevalueofthe"output"cellSimulationcanbeusedtoanalyzethesetypesofmodels5IntroductiontoSimulationArandomvariableisanyvariablewhosevaluecannotbepredictedorsetwithcertai

5、nty.Many“inputcells”inspreadsheetmodelsareactuallyrandomvariables.Forexample:thefuturecostofrawmaterialsfutureinterestratesfuturenumberofemployeesinafirmexpectedproductdemandDecisionsmadeusinguncertaininformationofteninvolverisk.Whatrisks?6RandomVariables&RiskUsingexpectedvaluesforunce

6、rtaincellstellsusnothingaboutthevariabilityoftheperformancemeasure.Supposean$1,000investmentisexpectedtoreturn$2,000intwoyears.Wouldyouinvestif...theoutcomescouldrangefrom$1,060to$4,000?theoutcomescouldrangefrom$0to$2,100?Alternativeswiththesameexpectedvaluemayinvolveverydifferentlevel

7、sofrisk.7WhyAnalyzeRisk?Best-Case/Worst-CaseAnalysisWhat-ifAnalysisSimulationMethodsofRiskAnalysis8Bestcase-pluginthemostoptimisticvaluesforeachoftheuncertaincells.Worstcase-pluginthemostpessimisticvaluesforeachoftheuncertaincells.Thisiseasytodoandboundstheoutcomes,buttellsusnothinga