Simulation?

1. Simulation - Introduction

2. Simulation? • Simulation: “… imitation of a dynamic system using a computer model in order to evaluate and improve system performance.” • By studying the behavior of a model one can gain insights about the behavior of the actual system • Focus will be on discrete-event simulation • Models the effects of the events in a system as they occur over time • Employs statistical methods for generating random behavior and estimating model performance

3. Why simulate? • Provides a way to validate whether or not the best decisions are being made • It is a powerful planning and decision-making tool • Simulation promotes a try-it-and-see attitude that stimulates innovation and encourages thinking “outside-the-box”

4. What makes simulation such a powerful planning and decision-making tool? • Captures system interdependencies • Accounts for variability in the system • Is versatile enough to model any system • Shows behavior over time • Is less costly, time consuming, and disruptive than experimenting on the actual system: “… if at first you don’t succeed, you probably should have simulated it.” • Provides information on multiple performance measures • Is visually appealing and engages people’s interest • Provides results that are easy to understand and communicate • Runs in compressed, real, or even delayed time • Forces attention to detail in a design: developing a model is, in itself, beneficial in that it forces one to think through the operational details of the process

5. Process of simulation experimentation • Process • Formulate a hypothesis about what design or operating policies work best • Set up simulation model • Conduct multiple replications of the experiment/simulation • Analyze simulation results and draw conclusions about hypothesis • Simulation itself is not a solution tool, but rather an evaluation tool: it describes how a defined system will behave; it does not prescribe how it should be designed

6. Typical applications of simulation • Simulation has been used to help plan and make improvements in many areas of both manufacturing and service industries:

7. Simulation is appropriate if the following criteria hold true • An operational (logical or quantitative) decision is being made • The process being analyzed is well defined and repetitive • Activities and events exhibit some interdependency and variability • The cost impact of the decision is greater than the cost of doing the simulation • The cost to experiment on the actual system is greater than the cost to do a simulation

8. Decision maker involvement in simulation • Decision maker should be heavily involved in, if not actually conducting, the simulation project • Often improvements suggest themselves in the very activity of building the model