AN ADVANCED SIMULATION METHOD (ASM) FOR MULTIPLE OBJECTIVE PROBLEMS Developments In Business Simulation & Experiential Exercises, Volume 17, 1990 183 AN ADVANCED SIMULATION METHOD (ASM) FOR MULTIPLE OBJECTIVE PROBLEMS Roy J. Clinton, Northeast Louisiana University Marvin D. Troutt, Southern Illinois University ABSTRACT Proposed is an advanced simulation method (ASM) for multiple objective decision making (MODM) in an interactive optimization mode. It is an improvement over standard interactive simulation based on what if methods (WIM). Both methods are capable of solving MODM problems with numerous alternatives, however, by comparing solutions found with both methods the ASM was shown to be superior to traditional methods. A unique aspect of the ASM is its capability of reverse problem solving (RPS) wherein the decision-maker (DM) starts with a desired solution and works backward to determine the required inputs. In contrast, the WIM gives the results after the DM varies the inputs (a very time consuming process, since in most real problems there is an unlimited set of alternatives). The ASM is user friendly, considers non-linear objectives, allows the units of measurement of the various objectives to be different, and is more efficient than WIMs. A scaling algorithm adjusts for the diversity in impacts caused by MODM problems with heterogeneous objectives while a variable step size algorithm assists in finding the optimal solution. WIMs are the easiest interactive simulation methods to design and use. There are numerous computer supported WIMs. Solutions are found in an interactive process where the user observes the outputs while continuously changing inputs until outputs are satisfactory. If the relationships among objectives and constraints are very complex the user may have difficulty in selecting ideal values for the inputs e.g. given the constraints some selections may not be feasible, changing inputs in attempts to improve one objective may cause other objectives to deteriorate, etc. In WIMs, however, an experienced user has the flexibility to rapidly ascend to the best solution, since the user can immediately select ideal values, if known, for the inputs. THE ADVANCED SIMULATION METHOD An interactive simulation method, the ASM searches the solution space for an optimal solution. A fundamental task is finding the best search direction, such as the gradient of the user’s utility function. If we assume that the overall objective function can be approximated by a weighted linear function the best direction of improvement of each objective function is the gradient. Therefore the best direction of improvement of the linear approximation for the user's utility function is the weighted combination of the individual objective gradients. Similar to other MODM methods the ASM involves the conversion of the MODM problem, with assumed objective weights, into an equivalent vector- maximization problem. An algorithm solves the vector- maximization problem using forces of effort supplied by the DM, to improve each objective. The ASM provides as simple a method as possible for soliciting direction of improvement information, yet it lacks the limitations of ideal point knowledge and is parsimonious regarding inputs. Unlike other methods the user is not faced with the perplexing task of assigning weights to the various objectives and adjusting those weights as the environment changes. Nor does the ASM present numerous complex decision choices or ranking questions to the user. Instead, it presents good, solutions and asks the user to choose the best, and to specify desired improvements in the chosen solution. When presented with a set of objective values for some alternative solution the user applies different amounts of force, which are perceived, as appropriately needed, to improve each respective objective. The system then calculates the feasible inputs that are needed. This intuitively appealing notion of applying efforts of force relative to the outcome desired, e.g. the more effort applied the more improvement gained, is more familiar to and preferred by the typical user. The gradient direction is deduced in a mariner similar to using the method of Geoffrion et al (1972). A major hypothesis of this method is that forces (DM’s relative desires for improvement) estimate up to a positive scalar constant the gradient direction of the DMs utility. In MODM the DM wishes to simultaneously optimize several conflicting objective functions, which usually are measured in different units. Units of measurement may be dollars, number of items, number of workers, weight, days, etc. Before heterogeneous objectives can be combined they mist be scaled. Without scaling the ASM is virtually useless because it, like many other MODM methods, experiences a distortion due to the “magnitude of impact” problem. For example, if one objective is to minimize cost, measured in dollars, and another objective is to minimize inventory, measured in number of items on hand, there is considerable difference in the magnitudes of the units of measurement. Changes in inventory levels of inexpensive item will have a significant impact on the linear programming coefficient vector, while changes in cost elements will have little impact. This diversity of impacts gives erroneous results in the linear programming maximization problem. This is a serious problem since it appears that users have a natural expectation that equal forces produce equal benefits. We therefore equalize the impact that each objective has on the LP coefficient vector with a scaling algorithm. The procedure provides values for an adjusting constant for each product (force of improvement and the respective objective gradient). The application of a force of improvement by the user will then increase the impact of the respective objective relative to the amount of force applied, without undue influence from its units of measurement. A procedure that uses the sum percent change (SPC) of the objectives provides a basis for determining the interval search lengths. This procedure is based on the assumption that as the DM’ compromise solution approaches the optimal solution the amount of change in objective values diminishes with each iteration. Summary Although the number of trial solutions and the time required were significantly reduced when using the ASM solutions achieved were much better than with the WIM. Table of Contents Volume 17, 1990 The Impact of Decision Support Systems on the Effectiveness of Small Group Decisions - Revisited The Relationship Between Financial Performance and Other Measures of Learning on a Simulation Exercise Use and Effectiveness of an Analogy-Based Expert System Suggestions for Computerized Business Authors Dealing with Power: An Experiential Exercise Using Movie and Personal Diary Analysis Techniques A Model for Developing Student Skills and Assessing Outcomes Through Outdoor Training Computer-Aided Exercises Versus Workbook Exercises as Learning Facilitator in the Principles of Marketing Course An Exposition of Guilford's Si Model as a Means of Diagnosing and Generating Pedagogical Strategies in Collegiate Business Education Formal Planning and Simulation Team Performance: A Cross Sectional Approach Cases: Real Organizations in Real Time in the Classroom An Empirical Investigation of the Internal Validity of Marketing Simulation Game An Empirical Evaluation of the Pedagogical Value of Playing a Simulation Game in a Principles of Marketing Course Factors Affecting Effective Teaching of Strategic Planning: Some Preliminary Evidence An Experiential Exercise for Learning About the Relationship Between Organizational Form & the Project Management Process Accounting Communication Skills can be Taught in the Auditing Course Modeling Cost Functions in Computerized Business Simulation: An Application of Duality Theory and Sheppard's Lemma A Life Cycle Analysis of Decision Making for a Strategic Management Team What's the Problem? A Dynamic Model for Teaching Problem Solving Skills Experientially International Currency Fluctuations: Money$im, A Simulation Superstores: A Specialized Retailing Simulation Within a Specialized Marketing Curriculum Factors Affecting Student Perceptions of Learning in a Business Policy Game VC + EL = VL The Name Game: An Experiential Exercise in Intergroup Relations The Effects of Experiential Accounting Work Experience on Student Performance in Intermediate Accounting Courses The Results of Using the Experiential Activity Group Performance Evaluation in a Business Policy Setting Using a Legal Database to Describe the Legal Environment of Marketing (and Business) Matching Environmental Uncertainty and Organizational Configuration An Instructional Computer Simulation of Tampering in QC Executive Evaluation of Student Learning in the Looking Glass Simulation Group Personality Composition and Total Enterprise Simulation Performance An Expert System for Selecting Analytical Techniques for Analyzing Marketing Research Data Effects of Cognitive Styles on Responses in an In-Basket Simulation A Psychometric Analysis of Kolb's Revised Learning Style-Inventory Selecting and Developing Experiential Exercises Using Movies Application of a Real-World Strategic Management Model in the Classroom Demand Equations which Include Product Attributes Consumption as the Objective in Computer-Scored Total Enterprise Simulations The Effects of Decision Format and Evaluation on Simulation Performance, Decision Time, and Team Cohesion The Effects of Computer Related Assignments on Student Performance in Business Administration The Money Game: A Dynamic Simulation Including Random Shocks for Money and Banking Courses Methods for Evaluating Performance on Business Simulations: A Survey The Effects of Synergogy on the Policy Course: Significant Improvements in Student Learning and Teacher Evaluation Conditions and Outcomes of Trust in a Two-Person Bargaining Exercise Bankgame Enhancing Computer Business Simulation with the Use of VGA Graphics An Experiential Approach to Entrepreneurship An Advanced Simulation Method (ASM) for Multiple Objective Problems The Influence of Experiential learning Techniques on Student Recognition of Non-Primary Learning Styles Negotiating Mergers and Acquisitions: A Cocktail Napkin Approach Identification of Unintended Effects in Experiential Laboratory Exercises An Experimental Comparison of Paper and Pencil and Computer Aided Decision Support Tools Porting a Simulation from the IBM World to the Macintosh World A Transaction Cost Analysis of Experiential Learning The Development of Experiential Exercises for Courses in Entrepreneurship and Small Business Management The Assessment Center as and Experiential Classroom Exercise Pricing Strategy Algorithms for Playing Business Simulations Organizational Structures for International Operations: An Experiential Activity Simulation Emphasis in the Business School Capstone Course An Integrated Approach to Computerizing the Business Curriculum Cross-Cultural Business Negotiations Exercise Organizational Socialization and Gender Differences in Students at Work Understanding Student Work Experience: A Content-Analytic Approach Introducing Executive MBA Programs with Management Games An Analysis of Improvement in Business Decision Outcome with Sequential Use of Two Simulation Games Teaching Business Policy Utilizing Mass Lecture and Individual Case Labs Potholes Along the Road to Evaluating Learning Outcomes: The Case of Outdoor Management Training Experiential Learning for Interior Design Students: Using CADD, Lotus 1-2-3, and Wordperfect Cognitive Learning Using a Computer-Based, Qualitative Interactive Business Simulation Sex Discrimination: Does the Woman get the Job or Does the Best Man Win? A Search for Visual Aids to Support Experiential Learning Through the 1990's An Experimental Analysis fo the Effectiveness of Student Role-Playing in Sales Training How to Have Students Learn from their Term Projects Self-Evaluation Exercise (SEE): An Assessment of Class Contribution A Study of the Influence of Team Formation on Attitudes and Performance in Management Games A Hardware Based CIM Simulation Laboratory Model Test Substance Abuse in Organizations Micro Computer Training Models Teaching Forecasting, Cash Budgeting and Inventory Model Building Using SBTools A Comparison of the Effects of Experiential Learning Activities and Traditional Lecture Classes An Adjunct Writing Instruction Assistant, The Computer; With an Illustration Classroom Software for ABC Analysis Utilizing Information Processing Technology to Enhance the Business Policy Simulation Experience Progressive Cases Realistic Job Previews Vs. Traditional Job Previews: Experiencing the Differences and Understanding the Consequences Investment Analysis Using the Pragmatic Multiplier Approach A Computer Simulation Interface for Competitive and Firm Analysis Self-Assessment of Ethical Decision Making Predispositions Preparing Managers for Overseas Assignments An Inquiry into Japanese Marketing: Workshop on Teaching Japanese Marketing The Performance Appraisal Feedback Interview: A Role Play for Human Resources Management Teaching Counselor Selling techniques Using Experiential Techniques to Teach International Topics International Management Simulation Gaming: Current Status and Future Developments A Realism Comparison of Simulation Technologies/Methodologies A Time-Efficient Game to Illustrate Concepts Taught in Management Courses and Management Development Programs Teaching the Management of Technology The Concept of Face and the Applicability of Experiential Exercises in an Oriental Culture's