第六章 决策分析方法Word文档格式.docx

1、6.8.2DecisionAnalysisGuidance6.8.2.1SystemsAnalysis,Simulation,andPerformance6.8.2.2TradeStudies6.8.2.3Cost-Benefit6.8.2.4InfluenceDiagrams（影响图）6.8.2.5Trees（决策树）6.8.2.6Multi-Criteria（多目标决策分析）6.8.2.7Utility6.8.2.8Risk-InformedExampleSYSTEMS ENGINEERING PRINCIPLES AND PRACTICE9 DECISION ANALYSIS AND S

2、UPPORT 9.1 Decision Making （决策过程与因素、决策框架）9.5 Trade-Off Analysis （综合分析，权衡分析）9.1 DECISION MAKING Simple decision making typically requires nothing more than some basic information and intuition. For example, deciding what one will have for breakfast requires some information what food is available, wh

3、at cooking skill level is available, and how much time one has. The output of this simple decision is the food that is to be prepared. But complex decisions require more inputs, more outputs, and much more planning. Furthermore, information that is collected needs to be organized, integrated （or fus

4、ed）, and presented to decision makers in such a way as to provide adequate support to make good decisions. Figure 9.1 depicts a simplified decision - making process for complex decisions. A more detailed process will be presented later in the chapter.Figure 9.1 Basic decision-making process.Obviousl

5、y, this appears to be rather cumbersome. However, how much time, energy, and the level of resource commitment devoted to each stage will be dependent on the type, complexity, and scope of the decision required. Formal decisions, typical in large government acquisition programs, may take years, while

6、 component decisions for a relatively simple system may require only hours or less. Each stage requires a finite amount of time. Even “ making the decision ” is not necessarily instantaneous. For example, if more than a single person must make and approve the decision, this stage may be quite length

7、y. If consensus is required, then this stage may become quite involved, and would include political as well as technical and programmatic considerations. Government legislatures are good examples in understanding the resources required in each step. Planning, gathering, and organizing are usually co

8、mpleted by staffs and through public and private hearings. The stage, making the decision, is actually an involved process that includes political maneuvering, deal making, marketing, campaigning, and posturing. This stage has lasted months in many cases. Regardless of the type of decision, or the f

9、orum within which the decision will be made, there are many factors that must be considered to initiate and complete the planning stage. Factors in the Decision - Making Process Complex decisions require an understanding of the multidimensionality of the process before an appropriate and useful deci

10、sion can be made. The following factors need to be considered as part of the planning stage. Goals and Objectives. Before making decisions, one needs to ask: what are the goals and objectives of the stakeholders? These will probably be different at different levels of the organization. The goals of

11、a line supervisor will be different than a program manager. Which holds the higher priority? And what are the goals of management above the decision maker? The decision should be made to satisfy （as far as possible） the goals and objectives of the important stakeholders. Decision Type. The decision

12、maker needs to understand the type of decision required. Many bad decisions stem from a misunderstanding about the type required. Is the decision binary? Maybe the decision is concerned with a permission of some sort. In these cases, a simple yes/no decision is required. Other binary decisions may n

13、ot be yes or no, but a choice between two alternatives, make or buy being a classic example. More complex decisions typically involve one or more choices among a set of alternatives. Lastly, the decision maker needs to understand who and what will be affected. Is the decision purely technical, or is

14、 there a personal element? Providing the wrong type of decision will certainly lead to significantly negative consequences. In the same vein, understanding who needs to be included in the decision is vital. Is this decision to be made by an individual? Or is a consensus among a group required? Who n

15、eeds to approve the decision before it is implemented? The answers to these questions influences when, and how, decisions will be made. Decision Context. Understanding the scope of the decision is also essential to making a proper decision. A global （or enterprise - wide） decision will be much diffe

16、rent than a system component decision. The consequences of a wrong decision will be far -reaching if the decision affects the enterprise, for example. Context involves understanding the problem or issue that led to a decision point. This will be difficult since context has many dimensions, leading t

17、o different goals and objectives for your decision maker: technical, involving physical entities, such as subsystem decisions; financial, involving investment instruments and quantities; personnel, involving people; process, involving business and technical procedures, methods, and techniques; progr

18、ammatic, involving resource allocations （including time, space, and funding）; temporal, meaning the time frame in which a decision is needed （this may be dynamic）; and legacy, involving past decisions. Stakeholders. Stakeholders can be defined as anyone （people or organizations） who will be affected

19、 by the results of the decision. Understanding who the stakeholders are with respect to a decision needs to be established before a decision is made. Many times, this does not occur stakeholders are not recognized before a decision is made. Yet, once the decision is announced or implemented, we can

20、be sure that all who are affected will make their opinion heard. Legacy Decisions. Understanding what relevant decisions have been made in the past helps with both the context （described above） and the environment in which the current decision must be made. Consequences and stakeholders can be ident

21、ified more readily if the decision maker has knowledge of the past. Supporting Data. Finally, necessary supporting data for the decision need to be provided in a timely fashion. A coherent and timely data collection plan is needed to ensure proper information can be gathered to support the decision.

22、 Accuracy in data collected is dependent on the decision type and context. Many times, decisions are delayed unnecessarily because greater accuracy than needed was demanded before the decision maker would act. Decision Framework As mentioned above, understanding the type of decision needed is critic

23、al in planning for and executing any process. Several decision frameworks are available in the literature to assist in understanding the decision type. In Table 9.1 , we present a framework that is a combination of several.TABLE 9.1 Decision FrameworkScope of ControlType ofDecisionOperationalManager

24、ialStrategic planningTechnology neededStructuredKnownprocedures algorithmsPolicies Laws Trade - off analysis LogicHistorical Goal - oriented task analysisInformation systemsSemistructuredTailored Heuristicspolicies Heuristics Causality ROI ProbabilitiesDecision support UnstructuredIntuition Experime

25、ntalCreativity TheoryExpert There are many ways to categorize decisions. Our categorization focuses on three types of decisions: structured, semistructured, and unstructured. Structured. These types of decisions tend to be routine, in that the context is well understood and the decision scope is kno

26、wn. Supporting information is usually available, and minimal organization or processing is necessary to make a good decision. In many cases, standards are available, either globally or within an organization, to provide solution methods. Structured decisions have typically been made in the past; thu

27、s, a decision maker has a historical record of similar or exact decisions made like the one he is facing. Semistructured. These types of decisions fall outside of “ routine. ” Although similar decisions may have been made, circumstances are different enough that past decisions are not a clear indica

28、tor of the right decision choice. Typically, guidance is available though, even when specific methods are not. Many systems engineering decisions fall within the category. Unstructured. Unstructured decisions represent complex problems that are unique and typically one-time. Decisions regarding new

29、technologies tend to fall into this category due to the lack of experience or knowledge of the situation. First - time decisions fall into this category. As experience grows and decisions are tested, they may transition from an unstructured decision to the semistructured category. In addition to the

30、 type, the scope of control is important to recognize. Decisions within each scope are structured differently, have different stakeholders, and require different technologies to support. Operational. This is the lowest scope of control that systems engineering is concerned about. Operational control

31、 is at the practitioner level the engineers, analysts, architects, testers, and so on, who are performing the work. Many decisions at this scope of control involve structured or semistructured decisions. Heuristics, procedures, and algorithms are typically available to either describe in detail when and how decisions should be made or at least to provide guidelines to decision making. In rare cases, when new technologies are