What is a simulation (revised)? • A simulation simply predicts the performance of an operations system under a specific set of inputs. • The simulation is an experimental approach to modelling, that is, a “what-if” analysis tool. • These four aspects (operations systems, purpose, simplification and experimentation) are now added to the previous definition so that simulation is defined as: “Experimentation with a simplified imitation (on a computer) of an operations system as it progresses through time, for the purpose of better understanding and/or improving that system.”