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An Introduction to Simulation

Simulation is the use of models to help show how a system behaves, to give a prediction or for training. Many people have experienced a form of simulation when they did First Aid training by practicing mouth-to-mouth resuscitation on a dummy but this is not the type of simulation that SimLean uses. In healthcare as in most other complex environments computer models are increasingly used and this is what SimLean uses too1.

A simulation is an experiment that uses a model of a process to predict behaviour over time i.e. it is dynamic. Just like in the real world, patients can arrive at different rates with different conditions and their treatment can only begin when specified resources (admin staff, clinical staff, equipment and rooms) are available. If resources are not available then queues form, just like in the real world. Queues grow and shrink during the course of the simulation and we can capture data about patient numbers, waiting times and utilisation.

A SimLean simulation model captures the logic of processes, it does not attempt to represent this as a mathematical equation (that would be either impossible or over-simplified) but as a set of quite simple rules. These rules are often implied by the arrows connecting activities on a process map. They can also be found by asking people involved in a process how and when they interact with other staff and most importantly with patients. Designs for improved processes can also be used to build a model and then test it by simulation. The benefit of simulation is that we can do this without disrupting current activity and without affecting patient safety.

The validity of a simulation depends on what it is to be used for. All models, no matter what their purpose or how they are built, are and must be simplifications. No model is perfect in any absolute sense but a good model should help people make better informed decisions. The level of detail used in SimLean Educate and SimLean Facilitate models has been chosen to reflect the needs of typical improvement events and/or workshops and the level of data that is available or can be identified quickly.


1. the particular type of simulation used by SimLean is called Discrete Event Simulation

detailed Information

Robinson, S. (2004). Simulation: The Practice of Model Development and Use. Wiley, Chichester, UK.