第八章 决策分析

Decision Analysis Terminology
• • • The decision maker is the individual or group responsible for making the decision. 决 策者是对一个决策负责人或团体 The alternatives are the options for the decision to be made. 备择方案是决策者将作 出的决策的选项 The outcome is affected by random factors outside the control of the decision maker. These random factors determine the situation that will be found when the decision is executed. Each of these possible situations is referred to as a possible state of nature. 决策的结果受到决策者无法控制的随即因素的影响，这些随即因素决定了决策者 执行中的各种状况，每一种可能的状况被称为可能的自然状态 The decision maker generally will have some information about the relative likelihood of the possible states of nature. These are referred to as the prior probabilities. 这些估 计用概率的形式表达出来就被称为特定自然状态的先验概率
Prior Probabilities
State of Nature
The tract of land contains oil The tract of land is dry (no oil)
Prior Probability
0.25 0.75
Payoff Table (Profit in $Thousands)
Table of Contents Chapter 12 (Decision Analysis)
Decision Analysis Examples 12.2–12.3 A Case Study: The Goferbroke Company Problem (Section 12.1) 12.4–12.8 Decision Criteria (Section 12.2) 12.9–12.13 Decision Trees (Section 12.3) 12.14–12.19 Sensitivity Analysis with Decision Trees (Section 12.4) 12.20–12.24 Checking Whether to Obtain More Information (Section 12.5) 12.25–12.27 Using New Information to Update the Probabilities (Section 12.6) 12.28–12.35 Decision Tree to Analyze a Sequence of Decisions (Section 12.7) 12.36–12.39 Sensitivity Analysis with a Sequence of Decisions (Section 12.8) 12.40–12.47 Using Utilities to Better Reflect the Values of Payoffs (Section 12.9)12.48–12.64
The Maximin Criterion
• • • The maximin criterion is the decision criterion for the total pessimist. It focuses only on the worst that can happen. Procedure:
– Identify the maximum payoff from any state of nature for each alternative. – Find the maximum of these maximum payoffs and choose this alternative.
State of Nature Alternative Drill for oil Sell the land Oil 700 90 Dry –100 90 Maximum in Row 700 Maximax 90
Decision Analysis
• Managers often must make decisions in environments that are fraught with uncertainty. 管理人员常常要在更多不确定性的环境中进行决策 Some Examples
– A government contractor bidding on a new contract. 一个政府工程承包商投标一个新合同 • What will be the actual costs of the project? 工程实际成本是多少 • Which other companies might be bidding? 哪些公司会投标 • What are their likely bids? 他们可能的投标价是多少 An agricultural firm selecting the mix of crops and livestock for the season. 一个农业公司为 即将到来的季节选择农作物和家畜的组合 • What will be the weather conditions? 天气状况如何 • Where are prices headed? 价格趋势是什么样的 • What will costs be? 成本会是多少 An oil company deciding whether to drill for oil in a particular location. 一个石油公司决策是 否在一个特定的地点钻探石油 • How likely is there to be oil in that location? 那里有石油的可能性是多少 • How much? 有多少石油 • How deep will they need to drill? 他们需要钻探多深 • Should geologists investigate the site further before drilling? 钻探前是否需要地质学家 做进一步的勘查
– Identify the minimum payoff from any state of nature for each alternative. – Find the maximum of these minimum payoffs and choose this alternative.
Decision Analysis 决策分析
• • Managers often must make decisions in environments that are fraught with uncertainty. 管理人员常常要在更多不确定性的环境中进行决策 Some Examples
– A manufacturer introducing a new product into the marketplace 制造商向市场推 出新产品 • What will be the reaction of potential customers? 潜在顾客将会作出什么反 应？ • How much should be produced? 制造商应该生产多少产品 • Should the product be test-marketed? 在决定全面分销前是否要进行试销 • How much advertising is needed? 应当打多少广告 – A financial firm investing in securities 一个金融公司投资有价证券 • Which are the market sectors and individual securities with the best prospects? 哪些市场板块和单个有价证券前景最好 • Where is the economy headed? 经济趋势如何 • How about interest rates? 利率会怎样变化 • How should these factors affect the investment decisions? 这些因素如何影响 投资决策
State of Nature
Alternative Drill for oil Sell the land Prior probability Oil 700 90 0.25 Dry –100 90 0.75
The Maximax Criterion
• • • The maximax criterion is the decision criterion for the eternal optimist. It focuses only on the best that can happen. Procedure:
• •
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Another oil company has offered to purchase the tract of land for $90,000. 另 一个石油公司听说了这个报告，决定出价90，000美元来购买这块土地
Question: Should Goferbroke drill for oil or sell the tract?
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The Goferbroke Company Problem
• • The Goferbroke Company develops oil wells in unproven territory. 这家公司 在未经证实的地区钻探石油 A consulting geologist has reported that there is a one-in-four chance of oil on a particular tract of land. 一位咨询地质家刚刚告诉马克斯，他认为这块土 地有四分之一的概率有石油 Drilling for oil on this tract would require an investment of about $100,000. 在 这块土地上钻探石油需要大概100，000美元的投资 If the tract contains oil, it is estimated that the net revenue generated would be approximately $800,000.如果这块地里有石油，那么他们会能获得800， 000美元的净收入
Prospective Profits
Profit Status of Land Alternative Drill for oil Sell the land Chance of status $700,000 90,000 1 in 4 –$100,000 90,000 3 in 4 Oil Dry
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Each combination of a decision alternative and a state of nature results in some outcome. The payoff is a quantitative measure of the value to the decision maker of the outcome. It is often the monetary value. 每一种决策的备择方案及自然状态都会导致某种结果， 收益是衡量决策结果对决策者的价值的量化指标