第六章 决策分析方法Word文档格式.docx

第六章 决策分析方法Word文档格式.docx

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6.8.2 

Decision 

Analysis 

Guidance

6.8.2.1 

Systems 

Analysis, 

Simulation, 

and 

Performance 

6.8.2.2 

Trade 

Studies

6.8.2.3 

Cost-Benefit 

6.8.2.4 

Influence 

Diagrams（影响图）

6.8.2.5 

Trees 

（决策树）

6.8.2.6 

Multi-Criteria 

（多目标决策分析）

6.8.2.7 

Utility 

6.8.2.8 

Risk-Informed 

Example 

②《SYSTEMSENGINEERINGPRINCIPLESANDPRACTICE》

9DECISIONANALYSISANDSUPPORT

9.1DecisionMaking（决策过程与因素、决策框架）

9.5Trade-OffAnalysis（综合分析，权衡分析）

9.1DECISIONMAKING

Simpledecisionmakingtypicallyrequiresnothingmorethansomebasicinformationandintuition.Forexample,decidingwhatonewillhaveforbreakfastrequiressomeinformation—whatfoodisavailable,whatcookingskilllevelisavailable,andhowmuchtimeonehas.Theoutputofthissimpledecisionisthefoodthatistobeprepared.Butcomplexdecisionsrequiremoreinputs,moreoutputs,andmuchmoreplanning.Furthermore,informationthatiscollectedneedstobeorganized,integrated（orfused）,andpresentedtodecisionmakersinsuchawayastoprovideadequatesupporttomake"

good"

decisions.

Figure9.1depictsasimplifieddecision-makingprocessforcomplexdecisions.Amoredetailedprocesswillbepresentedlaterinthechapter.

Figure9.1Basicdecision-makingprocess.

Obviously,thisappearstoberathercumbersome.However,howmuchtime,energy,andthelevelofresourcecommitmentdevotedtoeachstagewillbedependentonthetype,complexity,andscopeofthedecisionrequired.Formaldecisions,typicalinlargegovernmentacquisitionprograms,maytakeyears,whilecomponentdecisionsforarelativelysimplesystemmayrequireonlyhoursorless.

Eachstagerequiresafiniteamountoftime.Even“makingthedecision”isnotnecessarilyinstantaneous.Forexample,ifmorethanasinglepersonmustmakeandapprovethedecision,thisstagemaybequitelengthy.Ifconsensusisrequired,thenthisstagemaybecomequiteinvolved,andwouldincludepoliticalaswellastechnicalandprogrammaticconsiderations.Governmentlegislaturesaregoodexamplesinunderstandingtheresourcesrequiredineachstep.Planning,gathering,andorganizingareusuallycompletedbystaffsandthroughpublicandprivatehearings.Thestage,makingthedecision,isactuallyaninvolvedprocessthatincludespoliticalmaneuvering,dealmaking,marketing,campaigning,andposturing.Thisstagehaslastedmonthsinmanycases.

Regardlessofthetypeofdecision,ortheforumwithinwhichthedecisionwillbemade,therearemanyfactorsthatmustbeconsideredtoinitiateandcompletetheplanningstage.

FactorsintheDecision-MakingProcess

Complexdecisionsrequireanunderstandingofthemultidimensionalityoftheprocessbeforeanappropriateandusefuldecisioncanbemade.Thefollowingfactorsneedtobeconsideredaspartoftheplanningstage.

GoalsandObjectives.Beforemakingdecisions,oneneedstoask:

whatarethegoalsandobjectivesofthestakeholders?

Thesewillprobablybedifferentatdifferentlevelsoftheorganization.Thegoalsofalinesupervisorwillbedifferentthanaprogrammanager.Whichholdsthehigherpriority?

Andwhatarethegoalsofmanagementabovethedecisionmaker?

Thedecisionshouldbemadetosatisfy（asfaraspossible）thegoalsandobjectivesoftheimportantstakeholders.

DecisionType.Thedecisionmakerneedstounderstandthetypeofdecisionrequired.Manybaddecisionsstemfromamisunderstandingaboutthetyperequired.Isthedecisionbinary?

Maybethedecisionisconcernedwithapermissionofsomesort.Inthesecases,asimpleyes/nodecisionisrequired.Otherbinarydecisionsmaynotbeyesorno,butachoicebetweentwoalternatives,makeorbuybeingaclassicexample.Morecomplexdecisionstypicallyinvolveoneormorechoicesamongasetofalternatives.Lastly,thedecisionmakerneedstounderstandwhoandwhatwillbeaffected.Isthedecisionpurelytechnical,oristhereapersonalelement?

Providingthewrongtypeofdecisionwillcertainlyleadtosignificantlynegativeconsequences.

Inthesamevein,understandingwhoneedstobeincludedinthedecisionisvital.Isthisdecisiontobemadebyanindividual?

Orisaconsensusamongagrouprequired?

Whoneedstoapprovethedecisionbeforeitisimplemented?

Theanswerstothesequestionsinfluenceswhen,andhow,decisionswillbemade.

DecisionContext.Understandingthescopeofthedecisionisalsoessentialtomakingaproperdecision.Aglobal（orenterprise-wide）decisionwillbemuchdifferentthanasystemcomponentdecision.Theconsequencesofawrongdecisionwillbefar-reachingifthedecisionaffectstheenterprise,forexample.Contextinvolvesunderstandingtheproblemorissuethatledtoadecisionpoint.Thiswillbedifficultsincecontexthasmanydimensions,leadingtodifferentgoalsandobjectivesforyourdecisionmaker:

●technical,involvingphysicalentities,suchassubsystemdecisions;

●financial,involvinginvestmentinstrumentsandquantities;

●personnel,involvingpeople;

●process,involvingbusinessandtechnicalprocedures,methods,andtechniques;

●programmatic,involvingresourceallocations（includingtime,space,andfunding）;

●temporal,meaningthetimeframeinwhichadecisionisneeded（thismaybedynamic）;

and

●legacy,involvingpastdecisions.

Stakeholders.Stakeholderscanbedefinedasanyone（peopleororganizations）whowillbeaffectedbytheresultsofthedecision.Understandingwhothestakeholdersarewithrespecttoadecisionneedstobeestablishedbeforeadecisionismade.Manytimes,thisdoesnotoccur—stakeholdersarenotrecognizedbeforeadecisionismade.Yet,oncethedecisionisannouncedorimplemented,wecanbesurethatallwhoareaffectedwillmaketheiropinionheard.

LegacyDecisions.Understandingwhatrelevantdecisionshavebeenmadeinthepasthelpswithboththecontext（describedabove）andtheenvironmentinwhichthecurrentdecisionmustbemade.Consequencesandstakeholderscanbeidentifiedmorereadilyifthedecisionmakerhasknowledgeofthepast.

SupportingData.Finally,necessarysupportingdataforthedecisionneedtobeprovidedinatimelyfashion.Acoherentandtimelydatacollectionplanisneededtoensureproperinformationcanbegatheredtosupportthedecision.Accuracyindatacollectedisdependentonthedecisiontypeandcontext.Manytimes,decisionsaredelayedunnecessarilybecausegreateraccuracythanneededwasdemandedbeforethedecisionmakerwouldact.

DecisionFramework

Asmentionedabove,understandingthetypeofdecisionneedediscriticalinplanningforandexecutinganyprocess.Severaldecisionframeworksareavailableintheliteraturetoassistinunderstandingthedecisiontype.InTable9.1,wepresentaframeworkthatisacombinationofseveral.

TABLE9.1DecisionFramework

ScopeofControl

Typeof

Decision

Operational

Managerial

Strategicplanning

Technologyneeded

Structured

Known

procedures

algorithms

PoliciesLaws

Trade-off

analysis

Logic

Historical

Goal-oriented

taskanalysis

Information

systems

Semistructured

Tailored

Heuristics

policies

Heuristics

CausalityROI

Probabilities

Decision

support

Unstructured

Intuition

Experimental

Creativity

Theory

Expert

Therearemanywaystocategorizedecisions.Ourcategorizationfocusesonthreetypesofdecisions:

structured,semistructured,andunstructured.

Structured.Thesetypesofdecisionstendtoberoutine,inthatthecontextiswellunderstoodandthedecisionscopeisknown.Supportinginformationisusuallyavailable,andminimalorganizationorprocessingisnecessarytomakeagooddecision.Inmanycases,standardsareavailable,eithergloballyorwithinanorganization,toprovidesolutionmethods.Structureddecisionshavetypicallybeenmadeinthepast;

thus,adecisionmakerhasahistoricalrecordofsimilarorexactdecisionsmadeliketheoneheisfacing.

Semistructured.Thesetypesofdecisionsfalloutsideof“routine.”Althoughsimilardecisionsmayhavebeenmade,circumstancesaredifferentenoughthatpastdecisionsarenotaclearindicatoroftherightdecisionchoice.Typically,guidanceisavailablethough,evenwhenspecificmethodsarenot.Manysystemsengineeringdecisionsfallwithinthecategory.

Unstructured.Unstructureddecisionsrepresentcomplexproblemsthatareuniqueandtypicallyone-time.Decisionsregardingnewtechnologiestendtofallintothiscategoryduetothelackofexperienceorknowledgeofthesituation.First-timedecisionsfallintothiscategory.Asexperiencegrowsanddecisionsaretested,theymaytransitionfromanunstructureddecisiontothesemistructuredcategory.Inadditiontothetype,thescopeofcontrolisimportanttorecognize.Decisionswithineachscopearestructureddifferently,havedifferentstakeholders,andrequiredifferenttechnologiestosupport.

Operational.Thisisthelowestscopeofcontrolthatsystemsengineeringisconcernedabout.Operationalcontrolisatthepractitionerlevel—theengineers,analysts,architects,testers,andsoon,whoareperformingthework.Manydecisionsatthisscopeofcontrolinvolvestructuredorsemistructureddecisions.Heuristics,procedures,andalgorithmsaretypicallyavailabletoeitherdescribeindetailwhenandhowdecisionsshouldbemadeoratleasttoprovideguidelinestodecisionmaking.Inrarecases,whennewtechnologiesare