Quản trị kinh doanh - Chapter 13: Operational decision - Making tools: Simulation

Chapter 13Operational Decision-Making Tools:SimulationLecture OutlineMonte Carlo SimulationComputer Simulation with ExcelAreas of Simulation ApplicationSupplement 13-2SimulationMathematical and computer modeling technique for replicating real-world problem situationsModeling approach primarily used to analyze probabilistic problemsIt does not normally provide a solution; instead it provides information that is used to make a decisionPhysical simulationSpace flights, wind tunnels, treadmills for tiresMathematical-computerized simulationComputer-based replicated modelsCopyright 2011 John Wiley & Sons, IncSupplement 13-3Monte Carlo SimulationSelect numbers randomly from a probability distributionUse these values to observe how a model performs over time Random numbers each have an equal likelihood of being selected at randomCopyright 2011 John Wiley & Sons, IncSupplement 13-4Probability Distribution of DemandCopyright 2011 John Wiley & Sons, IncSupplement 13-5LAPTOPS DEMANDED FREQUENCY OF PROBABILITY OF PER WEEK, x DEMAND DEMAND, P(x) 0 20 0.20 1 40 0.40 2 20 0.20 3 10 0.10 4 10 0.10 100 1.00Roulette Wheel of DemandCopyright 2011 John Wiley & Sons, IncSupplement 13-6908060200x = 2x = 0x = 4x = 3x = 1Generating Demand from Random NumbersCopyright 2011 John Wiley & Sons, IncSupplement 13-7 DEMAND, RANGES OF RANDOM NUMBERS, x r 0 0-19 1 20-59 r = 39 2 60-79 3 80-89 4 90-99Random Number TableCopyright 2011 John Wiley & Sons, IncSupplement 13-815 Weeks of DemandCopyright 2011 John Wiley & Sons, IncSupplement 13-9WEEK r DEMAND (x) REVENUE (S) 1 39 1 4,300 2 73 2 8,600 3 72 2 8,600 4 75 2 8,600 5 37 1 4,300 6 02 0 0 7 87 3 12,900 8 98 4 17,200 9 10 0 0 10 47 1 4,300 11 93 4 17,200 12 21 1 4,300 13 95 4 17,200 14 97 4 17,200 15 69 2 8,600  = 31 $133,300Computing Expected DemandCopyright 2011 John Wiley & Sons, IncSupplement 13-10E(x) = (0.20)(0) + (0.40)(1) + (0.20)(2) + (0.10)(3) + (0.10)(4) = 1.5 laptops per weekDifference between 1.5 and 2.07 is due to small number of periods analyzed (only 15 weeks)Steady-state resultaverage result which stays constant after enough trialsEstimated average demand = 31/15 = 2.07 laptops/weekRandom Numbers in ExcelCopyright 2011 John Wiley & Sons, IncSupplement 13-11Simulation in ExcelCopyright 2011 John Wiley & Sons, IncSupplement 13-12Enter this formulain G6 and copy toG7:G20 Enter “=4300*G6”in H6 can copy toH7:H20Generate randomnumber for cellsF6:F20 with theformula “=RAND()”in F6 and copyingto F7:F20=AVERAGE(G6:G20)Simulation in ExcelCopyright 2011 John Wiley & Sons, IncSupplement 13-13Spreadsheet “frozen”at row 16 to showfirst 10 weeksand last 6Decision Making with SimulationCopyright 2011 John Wiley & Sons, IncSupplement 13-14=G6*50 entered intocell L6 and copiedto L7:L105This formula entered inG7 and copied toG8:G105=VLOOKUP(F6,LOOKUP,2)in H6 and copiedto H7:H105Shortages computedby entering=MIN(G6-H6,0)in I6 and copyingto I7:I105Decision Making with SimulationCopyright 2011 John Wiley & Sons, IncSupplement 13-15New formula for twolaptops orderedper week.Areas of Simulation ApplicationWaiting Lines/ServiceComplex systems for which it is difficult to develop analytical formulasDetermine how many registers and servers are needed to meet customer demandInventory ManagementTraditional models make the assumption that customer demand is certainSimulation is widely used to analyze JIT without having to implement it physicallyCopyright 2011 John Wiley & Sons, IncSupplement 13-16Areas of Simulation ApplicationProduction and Manufacturing SystemsProduction scheduling, production sequencing, assembly line balancing, plant layout, and plant location analysisMachine breakdowns typically occur according to some probability distributionsCapital Investment and BudgetingCapital budgeting problems require estimates of cash flows, often resulting from many random variablesSimulation has been used to generate values of cash flows, market size, selling price, growth rate, and market shareCopyright 2011 John Wiley & Sons, IncSupplement 13-17Areas of Simulation ApplicationLogisticsRandom variables include, distance, transport modes, shipping rates, and schedulesAllows analysis of different distribution channelsService OperationsPolice departments, fire departments, post offices, hospitals, court systems, airportsComplex operations where only simulation can be employedEnvironmental and Resource AnalysisImpact of manufacturing plants, waste-disposal facilities, nuclear power plants, waste and population conditions, feasibility of alternative energy sourcesCopyright 2011 John Wiley & Sons, IncSupplement 13-18Copyright 2011 John Wiley & Sons, IncSupplement 13-19Copyright 2011 John Wiley & Sons, Inc.All rights reserved. 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