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Introduction to Decision Analysis. Decision analysis studies the process of making difficult decisions The objective is to update, model, and document the intuition of managers A structured approach to decision making is especially critical in group decision making - PowerPoint PPT Presentation
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MGT3303Michel Leseure
Introduction to Decision Analysis
• Decision analysis studies the process of making difficult decisions
• The objective is to update, model, and document the intuition of managers
• A structured approach to decision making is especially critical in group decision making
• Key importance in the case of resource decisions (operations strategy)
MGT3303Michel Leseure
Why are decisions difficult?
• Complexity– Simply keeping all the issues in mind at
one time is nearly imposible
• Uncertainty– Making a decision is especially difficult
when you are not sure about one decision variable’s state
• Multiple objectives• Different perspectives lead to different
conclusions
MGT3303Michel Leseure
Example
• Winter of 1985:– The Oregon Department of Agriculture
(ODA) faced an infestation of gypsy moth in Lane County in Western Oregon
– Forest industry representative call for an aggressive eradication campaign
MGT3303Michel Leseure
Alternatives
• Use BT, a bacterial insecticide– target specific– ecologically safe– reasonably effective
• Use Orthene, a chemical spray– registered as acceptable for home garden use– questions about its ultimate ecological effects– possible danger to humans
• Possible to use both
MGT3303Michel Leseure
Opinions
• Forestry officials: – Argue Orthene is more potent and is necessary to
ensure eradication
• Environmentalists:– Orthene potentially too dangerous
• Others– Already too late anyway
• Others...– Still time but decision/implementation has to be
made now
MGT3303Michel Leseure
Subjective Judgments
• In decisional contexts such as the one faced by ODA– objective data is lacking– a procedure determining an « optimal » decision
derived from objective data is of little use...– personal statements about uncertainty and value
become important inputs (no choice...)– Discovering and finalizing these judgments is a key
issue in decision analysis– Instead of criticizing them, we will learn how to
better assess and use them
MGT3303Michel Leseure
The Decision Analysis Process
• Identify the decision situation and understand objectives
• Identify alternatives• Decompose and model the problem
– model of problem structure– model of uncertainty– model of preferences
• Choose the best alternative• Sensitivity analysis• Is further analysis needed? yes/no?• Implement the chosen alternative
MGT3303Michel Leseure
Requisite Decision Models
• A model can be considered requisite only when no new intuitions emerge about the problem
• or when it contains everything that is essential for solving the problem
MGT3303Michel Leseure
Elements of a Decision Problem
• Values and objectives• Decisions to make• Uncertain events• Consequences
MGT3303Michel Leseure
Values and Objectives
• Value: used in its general sense « things that matter to you »
• Objective: Specific thing that you want to achieve
• The set of objectives taken up together make up the values
• Values are the reason for making the decision in the first place
• They define the decision context
MGT3303Michel Leseure
Objectives for Boeing’s Supercomputer
SupercomputerObjectives
CostFive-year costsCost of improved performance
PerformanceSpeedThroughputMemory SizeDisk SizeOn-site performance
User NeedsInstallation dateRoll in/Roll outEase of UseSoftware compatibilityMean timebetween failures
Operational NeedsSquare footageWater coolingOperator toolsTelecommuni--cationsVendor support
ManagementIssueVendor HealthUS OwnershipCommitmentto supercomputer
MGT3303Michel Leseure
Decision to Make
• Given a decisional context, one (or several) decision(s) has to be made
• In some cases, several decisions may have to be made in a sequence
Decision 1 Decision 3Decision 2
Time
MGT3303Michel Leseure
Uncertain Events
– Uncertain events are either linked to chance or are linked to a probability distribution
– Uncertain events have outcome– It is important to position uncertain events
appropriately between decisions
Decision 1 Decision 3Decision 2
Time
MGT3303Michel Leseure
Consequences
• After the last decision has been made and the last uncertain event has been resolved, the decision maker’s fate is finally determined
Decision 1 Decision 3Decision 2
Time
Consequence
MGT3303Michel Leseure
Example
PolicyDecision
AccidentManagement
DecisionsTime
Accident
Consequence:Cost $
Environmentaldamage
PR damage
Cause
Weather
Location
Weatherfor
Cleanup
Cost
EnvironmentalDamage
MGT3303Michel Leseure
Making Choices
• Decision Trees• Example: Texaco vs. Pennzoil• Decision trees and expected value
– certainty equivalent
MGT3303Michel Leseure
Decision Trees
• Decision trees are a graphical representation of a decision problem
Invest
Do not invest
Venture succeeds
Venture fails
Typical return earnedon less risky investment
Funds lost
Large return
MGT3303Michel Leseure
Decision Tree
Forecast
Evacuate
Stay
Storm hits Miami
Storm misses Miami
Safety Cost
Safe
Safe
Danger
High
Low
Low
MGT3303Michel Leseure
Cash Flows and Probabilities
• To each branch of the tree, we can attach– a probability– and/or, a cash flow– or any measure replacing monetary values
for a specific problem
MGT3303Michel Leseure
Case Study: Texaco vs. Pennzoil
• In early 1984, Pennzoil and Getty Oil agreed to the terms of a merger
• Before the signature of the formal agreement, Texaco offered Getty a substantially better price , and Gordon Getty (majority stockholder) defected on Pennzoil and sold to Texaco
MGT3303Michel Leseure
Case Study: Texaco vs. Pennzoil
• Pennzoil felt this was unfair practice and filed a lawsuit against Texaco, alleging that Texaco had interfered illegally in the the Pennzoil-Getty negotiations
• Pennzoil won the case in late 1985 and was awarded $11.1 billion – the largest settlement in the US at this point in time
• Texaco appealed and the settlement was reduced by $2 billion – but interest and penalty got the amount back to $10.3 billion
MGT3303Michel Leseure
Case Study: Texaco vs. Pennzoil
• Kinnear, Texaco’s CEO, announced that Texaco would file for bankruptcy if Pennzoil obtained court permission to secure the judgment by filing liens against Texaco’s assets
• Kinnear promised to fight the case all the way to the Supreme Court
MGT3303Michel Leseure
Texaco’s Offer
• In April 1987, just before Pennzoil started filing liens, Texaco offered to pay Pennzoil $2billion to settle the entire case
• Liedtke, chairman of Pennzoil, announced that his advisors estimated that a settlement of 3-5 billions would be fair
What should Liedtke do?
MGT3303Michel Leseure
Decision Tree SettlementAmount($billion)
2
Counteroffer$5 billion
5Texaco accepts $5 billion
Texacocounteroffers$3 billion
3Accepts $3 billion
Refuse
Final Court Decision
0510.3
Final Court Decision
05
10.3Texacorefusescounteroffer
Accepts $2 billion
MGT3303Michel Leseure
Subjective Probabilities
• In the decision tree, we are missing probability estimates of the each event
• For this lecture, we will take these probability values for granted
MGT3303Michel Leseure
Decision Tree SettlementAmount($billion)
2
Counteroffer$5 billion
5Texaco accepts $5 billion
Texacocounteroffers$3 billion
3Accepts $3 billion
Refuse
Final Court Decision
05
10.3
Final Court Decision
05
10.3Texacorefusescounteroffer
(0.17)
(0.33)(0.50)
(0.2)
(0.5)
(0.3)
(0.2)
(0.5)
(0.3)
Accepts $2 billion
MGT3303Michel Leseure
Expected Monetary Value
• Computing an expected monetary value is a way of selecting among risky alternative
• Computing expected values bring the problem back to a « certainty equivalent »
• What is the expected value of the court judgment?
MGT3303Michel Leseure
Expected Value of the Court Judgment
• EV = 0.2 * 10.3 + 0.5 * 5 + 0.3 * 0• EV = $ 4.56 billion
Final Court Decision
0510.3
(0.5)
(0.3)
(0.2)
It is possible to reduce the tree with this certaintyequivalent
MGT3303Michel Leseure
Reduced Tree
2
Counteroffer$5 billion
5Texaco accepts $5 billion
Texacocounteroffers$3 billion
3Accepts $3 billion
Refuse
Texaco refuses counteroffer
(0.17)
(0.33)
(0.50)4.56
4.56
Eliminated
Accepts $2 billion
MGT3303Michel Leseure
Expected Monetary Value of the Counteroffer
• What is the expected monetary value of Pennzoil $5 billion counter offer:
• EV = P(Texaco accepts) * 5 + P(Texaco refuse) * 4.56 + P(Texaco counteroffers) * 4.56
• EV = 4.63Liedtke should not accept the $2 billion offer, and should counter-offer $5 billion. If Texacorefuses, then the matter should be taken tocourt
MGT3303Michel Leseure
Reducing the Decision Tree
• In practice, we do not reduce the decision tree but report expected values on the nodes
MGT3303Michel Leseure
Resolved Decision Tree
2
4.63
Counteroffer$5 billion
5Texaco accepts $5 billion
Texacocounteroffers$3 billion
3Accepts $3 billion
4.56Refuse
Final Court Decision
0510.3
4.56Final Court Decision
0510.3
Texacorefusescounteroffer
(0.17)
(0.33)(0.50)
(0.2)
(0.5)
(0.3)
(0.2)
(0.5)
(0.3)
Accepts $2 billion
MGT3303Michel Leseure
Suggested Homework
• Problem S2-10, p. 70• Problem S2-13, p. 71