Question 2
Chapter 9:
Model-Based Decision Making: Optimization and Multi-Criteria Systems
Business Intelligence and Analytics: Systems for Decision Support
(10th Edition)
Business Intelligence and Analytics: Systems for Decision Support
(10th Edition)
Copyright © 2014 Pearson Education, Inc.
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Learning Objectives
Understand the basic concepts of analytical decision modeling
Describe how prescriptive models interact with data and the user
Understand some different, well-known model classes
Understand how to structure decision making with a few alternatives
Describe how spreadsheets can be used for analytical modeling and solution
(Continued )
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Learning Objectives
Explain the basic concepts of optimization and when to use them
Describe how to structure a linear programming model
Describe how to handle multiple goals
Explain what is meant by sensitivity analysis, what-if analysis, and goal seeking
Describe the key issues of multi-criteria decision making
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Opening Vignette
Midwest ISO Saves Billions by Better Planning of Power Plant Operations and Capacity Planning
Company background
Problem description
Proposed solution
Results
Answer & discuss the case questions…
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Questions for the Opening Vignette
In what ways were the individual companies in Midwest ISO better off being part of MISO as opposed to operating independently?
The dispatch problem was solved with a linear programming method. Explain the need of such method in light of the problem discussed in the case.
What were the two main optimization algorithms used? Briefly explain the use of each algorithm.
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Decision Support Systems Modeling
DSS modeling (optimization & simulation) contribute to organizational success. Examples include:
Pillowtex (see ProModel, 2013),
Fiat (see ProModel, 2006),
Procter & Gamble (see Camm et al., 1997),
and others.
INFORMS publications such as Interfaces, ORMS Today, and Analytics magazine have plenty of such example cases
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Application Case 9.1
Optimal Transport for ExxonMobil Downstream Through a DSS
Questions for Discussion
List three ways in which manual scheduling of ships could result in more operational cost as compared to the tool developed.
In what other ways can ExxonMobil leverage the decision support tool developed to expand and optimize their other business operations?
What are some strategic decisions that could be made by decision makers using the tool developed?
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Major Modeling Issues
Problem identification and environmental analysis (information collection)
Variable identification
Influence diagrams, cognitive maps
Forecasting/predicting
More information leads to better prediction
Multiple models: An MSS can include several models, each of which represents a different part of the decision-making problem
Categories of models >>>
Model management DBMS vs. MBDM
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Categories of Models
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Model Categories Static and Dynamic Models
Static Analysis
Single snapshot of the situation
Single interval
Steady state
Dynamic Analysis
Dynamic models
Evaluate scenarios that change over time
Time dependent
Represents trends and patterns over time
More realistic: Extends static models
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Application Case 9.2
Optimal Transport for ExxonMobil Downstream Through a DSS
Company
Problem description
Proposed solution
Results
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Model Categories Current Trends in Modeling
Development of Model/Solution Libraries
NEOS Server for Optimization
neos.mcs.anl.gov/neos/index.html
Resources link at informs.org
lionhrtpub.com/ORMS.shtml
Web-based modeling (optimization/simulation/ )
Multidimensional analysis (modeling)
Influence Diagrams
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Structure of Mathematical Models for Decision Support
Decision
Variables
Mathematical
Relationships
Uncontrollable
Variables
Result
Variables
Non-Quantitative Models (Qualitative)
Quantitative Models: Mathematically links decision variables, uncontrollable variables, and result variables
Independent Variables
Dependent Variable
Intermediate
Variables
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Examples – Components of Models
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The Structure of a Mathematical Model
The components of a quantitative model are linked together by mathematical (algebraic) expressionsequations or inequalities.
Example Profit –
whereP= profit, R= revenue, and C= cost
Example – Simple Present-Value –
whereP= present value, F= future cash-flow, i= interest-rate, and n = number of period (years)
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Modeling and Decision Making – Under Certainty, Uncertainty, and Risk
Certainty
Assume complete knowledge
All potential outcomes are known
May yield optimal solution
Uncertainty
Several outcomes for each decision
Probability of each outcome is unknown
Knowledge would lead to less uncertainty
Risk analysis (probabilistic decision making)
Probability of each of several outcomes occurring
Level of uncertainty => Risk (expected value)
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Modeling and Decision Making – Under Certainty, Uncertainty, and Risk
The Zones of Decision Making
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Application Case 9.3
American Airlines Uses Should-Cost Modeling to Assess the Uncertainty of Bids for Shipment Routes
Questions for Discussion
Besides reducing the risk of overpaying or underpaying suppliers, what are some other benefits AA would derive from its should be model?
Can you think of other domains besides air transportation where such a model could be used?
Discuss other possible methods with which AA could have solved its bid overpayment and underpayment problem.
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Decision Modeling with Spreadsheets
Spreadsheet
Most popular end-user modeling tool
Flexible and easy to use
Powerful functions (add-in functions)
Programmability (via macros)
What-if analysis and goal seeking
Simple database management
Seamless integration of model and data
Incorporates both static and dynamic models
Examples: Microsoft Excel, Lotus 1-2-3
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Application Case 9.4
Showcase Scheduling at Fred Astaire East Side Dance Studio
Company
Problem description
Proposed solution
Results
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Excel spreadsheet – static model example: (Simple loan calculation of monthly payments)
Static model example:
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Excel spreadsheet – Dynamic model example: Simple loan calculation of monthly payments and effects of prepayment
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Optimization via Mathematical Programming
Mathematical Programming
A family of tools designed to help solve managerial problems in which the decision maker must allocate scarce resources among competing activities to optimize a measurable goal
Optimal solution: The best possible solution to a modeled problem
Linear programming (LP): A mathematical model for the optimal solution of resource allocation problems. All the relationships are linear.
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Application Case 9.5
Spreadsheet Model Helps Assign Medical Residents
Company
Problem description
Proposed solution
Results
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LP Problem Characteristics
Limited quantity of economic resources
Resources are used in the production of products or services
Two or more ways (solutions, programs) to use the resources
Each activity (product or service) yields a return in terms of the goal
Allocation is usually restricted by constraints
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Linear Programming Steps
Identify the
Decision variables
Objective function
Objective function coefficients
Constraints
Capacities / Demands /
Represent the model
LINDO: Write mathematical formulation
EXCEL: Input data into specific cells in Excel
Run the model and observe the results
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Modeling in LP – An Example
The Product-Mix Linear Programming Model
MBI Corporation
Decision variable: How many computers to build next month?
Two types of mainframe computers: CC-7 and CC-8
Constraints: Labor limits, Materials limit, Marketing lower limits CC-7 CC-8 Rel Limit Labor (days) 300 500 <= 200,000 /mo Materials ($) 10,000 15,000 <= 8,000,000 /mo Units 1 >= 100 Units 1 >= 200 Profit ($) 8,000 12,000 Max Objective: Maximize Total Profit / Month
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LP Solution Algebraic Formulations
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LP Solution with Excel
Decision Variables:
X1: unit of CC-7
X2: unit of CC-8
Objective Function:
Maximize Z (profit)
Z=8000X1+12000X2
Subject To
300X1 + 500X2 ? 200K
10000X1 + 15000X2 ? 8000K
X1 ? 100
X2 ? 200
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Illustrating the Power of Spreadsheet Modeling
Election Resource Allocation Problem
Analysis of swing states for the 2012 election
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Common Optimization Models
Product-mix problems (how many of each product to produce for max profit)
Transportation (minimize cost of shipments)
Assignment (best matching of objects)
Investment (maximizing rate of return)
Network optimization models for planning and scheduling
Replacement (capital budgeting),
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Multiple Goals, Sensitivity Analysis, What-If Analysis, and Goal Seeking
Multiple Goals
Simple-goal vs. multiple goals
Vast majority of managerial problems has multiple goals (objectives) to achieve
Attaining simultaneous goals
Methods of handling multiple goals
Utility theory
Goal programming
Expression of goals as constraints, using LP
A points system
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Multiple Goals, Sensitivity Analysis, What-If Analysis, and Goal Seeking
Certain difficulties may arise when analyzing multiple goals
Difficult to obtain a single organizational goal
The importance of goals change over time
Goals and sub-goals are viewed differently
Goals change in response to other changes
Dynamics of groups of decision makers
Assessing the importance (priorities)
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Multiple Goals, Sensitivity Analysis, What-If Analysis, and Goal Seeking
Sensitivity analysis
It is the process of assessing the impact of change in inputs on outputs
Helps to
eliminate (or reduce) variables
revise models to eliminate too-large sensitivities
adding details about sensitive variables or scenarios
obtain better estimates of sensitive variables
alter a real-world system to reduce sensitivities
Can be automatic or trial and error
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Multiple Goals, Sensitivity Analysis, What-If Analysis, and Goal Seeking
What-if analysis
Assesses solutions based on changes in variables or assumptions (scenario analysis)
What if we change our capacity at the milling station by 40% [what would be the impact]
Goal seeking
Backwards approach, starts with the goal and determines values of inputs needed
Example is break-even point determination
In-order to break even (profit = 0), how many products do we have to sell each month
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Decision Analysis with Decision Tables and Decision Trees
Decision Tables a tabular representation of the decision situation (alternatives)
Investment Example
Goal: maximize the yield after one year
Yield depends on the status of the economy (the state of nature)
Solid growth
Stagnation
Inflation
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Decision Table – Investment Example: Possible Situations
1. If solid growth in the economy, bonds yield 12%; stocks 15%; time deposits 6.5%
2. If stagnation, bonds yield 6%; stocks 3%; time deposits 6.5%
3. If inflation, bonds yield 3%; stocks lose 2%; time deposits yield 6.5%
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Payoff decision variables (alternatives)
Uncontrollable variables (states of economy)
Result variables (projected yield)
Tabular representation:
Decision Table Investment Example: Decision Table
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Decision Table Investment Example: Treating Uncertainty
Optimistic approach
Pessimistic approach
Treating Risk/Uncertainty:
Use known probabilities
Expected values
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Decision Table Investment Example: Multiple Goals
Multiple goals
Yield, safety, and liquidity
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Decision Trees
Graphical representation of relationships
Multiple criteria approach
Demonstrates complex relationships
Cumbersome, if many alternatives exists
Tools include
Mind Tools Ltd., mindtools.com
TreeAge Software Inc., treeage.com
Palisade Corp., palisade.com
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Decision Trees An Example
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Multi-Criteria Decision Making with Pairwise Comparisons
Having more than one criterion makes decision-making process complicated
Usually some type of weighing algorithm is used to analyze such problems
The Analytic Hierarchy Process
Developed by Thomas Saaty (1995, 1996)
A very popular technique for MCDM
Popular Tools – ExpertChoice.com
Web-based Tools – Web-HIPRE (hipre.aalto.fi)
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Application Case 9.6
U.S. HUD Saves the House by Using AHP for Selecting IT Projects
Company
Problem description
Proposed solution
Results
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Tutorial – Applying AHP Using Web-HIPRE
Goal: select the most appropriate movie
Identify some criteria for making this decision
The main and sub-criteria for movie selection are
a. Genre: Action, Comedy, Sci-Fi, Romance
b. Language: English, Hindi
c. Day of Release: weekday, weekend
d. User/Critics Rating: High, Average, Low
Alternatives are the following current movies:
SkyFall, The Dark Knight Rises, The Dictator, Dabaang, Alien, and DDL
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Tutorial – Applying AHP Using Web-HIPRE
Step 1: define the goal, criteria, and alternatives
Web-HIBRE allows defining all of these and relationships within an easy-to-use Web-based interface.
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Tutorial – Applying AHP Using Web-HIPRE
Step 2: the main criteria are then ranked as they relate to the goal
A comparative ranking scale from 1 to 9 (with ascending order of importance) is used
The ranking is done using a Pairwise comparison procedure (i.e., divide-and-concur) between any two criteria for all combinations of twos
The tool readily normalizes the rankings of each of the main criteria over one another to a scale ranging from 0 to 1 and then calculates the row averages to arrive at an overall importance rating ranging from 0 to 1
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Tutorial – Applying AHP Using Web-HIPRE
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Tutorial – Applying AHP Using Web-HIPRE
Step 3: All of the subcriteria related to each of the main criteria are then ranked with their relative importance over one another
Step 4: Each alternative is ranked with respect to all of the subcriteria that are linked with the alternatives in a similar fashion using the relative scale of 09; then the overall importance of each alternative is calculated
Step 5: The final result are obtained from the composite priority analysis involving all the subcriteria and main criteria
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Tutorial – Applying AHP Using Web-HIPRE
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Tutorial – Applying AHP Using Web-HIPRE
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Tutorial – Applying AHP Using Web-HIPRE
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Chapter 10:
Modeling and Analysis: Heuristic Search Methods and Simulation
Business Intelligence and Analytics: Systems for Decision Support
(10th Edition)
Business Intelligence and Analytics: Systems for Decision Support
(10th Edition)
Copyright © 2014 Pearson Education, Inc.
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Learning Objectives
Explain the basic concepts of simulation and heuristics, and when to use them
Understand how search methods are used to solve some decision support models
Know the concepts behind and applications of genetic algorithms
Explain the differences among algorithms, blind search, and heuristics
(Continued )
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Learning Objectives
Understand the concepts and applications of different types of simulation
Explain what is meant by system dynamics, agent-based modeling, Monte Carlo, and discrete event simulation
Describe the key issues of model management
Copyright © 2014 Pearson Education, Inc.
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Opening Vignette
System Dynamics Allows Fluor
Corporation to Better Plan for Project and Change Management
Background
Problem description
Proposed solution
Results
Answer & discuss the case questions…
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Questions for the Opening Vignette
Explain the use of system dynamics as a simulation tool for solving complex problems.
In what ways was it applied in Fluor Corporation to solve complex problems?
How does a what-if analysis help a decision maker to save on cost?
In your own words, explain the factors that might have triggered the use of system dynamics to solve change management problems in Fluor Corporation
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Problem-Solving Search Methods
Search: choice phase of decision making
Search is the process of identifying the best possible solution / course of action [under limitations such as time, ]
Search techniques include
analytical techniques,
algorithms,
blind searching, and
heuristic searching
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Problem-Solving Search Methods
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Problem-Solving Search Methods – Algorithmic/Heuristic
Cuts the search space
Gets satisfactory solutions more quickly and less expensively
Finds good enough feasible solutions to complex problems
Heuristics can be
Quantitative
Qualitative (in ES)
Traveling Salesman Problem see the example next >>>
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Traveling Salesman Problem
What is it?
A traveling salesman must visit customers in several cities, visiting each city only once, across the country. Goal: Find the shortest possible route.
Total number of unique routes (TNUR):
TNUR = (1/2) (Number of Cities 1)!
Number of Cities TNUR
5 12
6 60
9 20,160
20 1.22 1018
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Traveling Salesman Problem
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Traveling Salesman Problem
Rule 1: Starting from home base, go to the closest city
Rule 2: Always follow an exterior route
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Application Case 10.1
Chilean Government Uses Heuristics to Make Decisions on School Lunch Providers
Questions for Discussion
What were the main challenges faced by JUNAEB?
What operation research methodologies were employed in achieving homogeneity across territorial units?
What other approaches could you use in this case study?
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When to Use Heuristics
When to Use Heuristics?
Inexact or limited input data
Complex reality
Reliable, exact algorithm not available
Computation time excessive
For making quick decisions
Limitations of Heuristics!
Cannot guarantee an optimal solution
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Tabu search
Intelligent search algorithm
Genetic algorithms
Survival of the fittest
Simulated annealing
Analogy to Thermodynamics
Ant colony and other Meta-heuristics
Modern Heuristic Methods
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Genetic Algorithms
It is a popular heuristic search technique
Mimics the biological process of evolution
Genetic algorithms
Software programs that learn/search in evolutionary manner, similar to the way biological systems evolve
An efficient, domain-independent search heuristic for a broad spectrum of problem domains
Main theme: Survival of the fittest
Moving toward better and better solutions by letting only the fittest parents create the future generations
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Evolutionary Algorithm
10010110
01100010
10100100
10011001
01111101
. . .
. . .
. . .
. . .
10010110
01100010
10100100
10011101
01111001
. . .
. . .
. . .
. . .
Selection
Reproduction
. Crossover
. Mutation
Current
generation
Next
generation
Elitism
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Each candidate solution is called a chromosome
A chromosome is a string of genes
Chromosomes can copy themselves, mate, and mutate via evolution
In GA we use specific genetic operators
Reproduction
Crossover
Mutation
GA Structure and GA Operators
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Genetic Algorithms – Example: The Vector Game
Description of the Vector Game
Identifying a string of 5 binary digits
Default Strategy: Random Trial and Error
Improved Strategy: Use of Genetic Algorithms
In an iterative fashion, using genetic algorithm process and genetic operators, find the opponents digit sequence
See your book for functional details
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Item: 1 2 3 4 5 6 7
Benefit: 5 8 3 2 7 9 4
Weight: 7 8 4 10 4 6 4
Knapsack holds a maximum of 22 pounds
Need to fill it for maximum benefit (one per item)
Solutions take the form of a string of 1s
Example Solution: 1 1 0 0 1 0 0
Means choose items 1, 2, 5:
Weight = 21, Benefit = 20
Evolver solution works in Microsoft Excel ?
A Classic GA Example: The Knapsack Problem
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Define the objective function and constraint(s)
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Identify the decision variables and their characteristics
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Observe and analyze the results
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Observe and analyze the results
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The Knapsack Problem at Evolver
Monitoring the solution generation process
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Genetic Algorithms
Limitations of Genetic Algorithms
Does not guarantee an optimal solution (often settles in a sub optimal solution / local minimum)
Not all problems can be put into GA formulation
Development and interpretation of GA solutions requires both programming and statistical skills
Relies heavily on the random number generators
Locating good variables for a particular problem and obtaining the data for the variables is difficult
Selecting methods by which to evolve the system requires experimentation and experience
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Genetic Algorithm Applications
Dynamic process control
Optimization of induction rules
Discovery of new connectivity topologies (NNs)
Simulation of biological models of behavior
Complex design of engineering structures
Pattern recognition
Scheduling, transportation, and routing
Layout and circuit design
Telecommunication, graph-based problems,
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Simulation
Simulation is the appearance of reality
It is often used to conduct what-if analysis on the model of the actual system
It is a popular DSS technique for conducting experiments with a computer on a comprehensive model of the system to assess its dynamic behavior
Often used when the system is too complex for other DSS techniques
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Application Case 10.3
Simulating Effects of Hepatitis B Interventions
Questions for Discussion
Explain the advantage of operations research methods such as simulation over clinical trial methods in determining the best control measure for Hepatitis B.
In what ways do the decision and Markov models provide cost-effective ways of combating the disease?
Discuss how multidisciplinary background is an asset in finding a solution for the problem described in the case.
Besides healthcare, in what other domain could such a modeling approach help reduce cost?
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Imitates reality and captures its richness both in shape and behavior
Represent versus Imitate
Technique for conducting experiments
Descriptive, not normative tool
Often to solve [i.e., analyze] very complex systems/problems
Simulation should be used only when a numerical optimization is not possible
Major Characteristics of Simulation
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Advantages of Simulation
The theory is fairly straightforward
Great deal of time compression
Experiment with different alternatives
The model reflects managers perspective
Can handle wide variety of problem types
Can include the real complexities of problems
Produces important performance measures
Often it is the only DSS modeling tool for non-structured problems
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Disadvantages of Simulation
Cannot guarantee an optimal solution
Slow and costly construction process
Cannot transfer solutions and inferences to solve other problems (problem specific)
So easy to explain/sell to managers, may lead to overlooking analytical solutions
Software may require special skills
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Simulation Methodology
Steps:
1. Define problem 5. Conduct experiments
2. Construct the model 6.
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