While System Dynamics could mean to understand how a system would respond to variations in internal and external situations over time, as a descipline it is the use of simulation models to understand and improve a system’s behaviour.

This includes modeling the system of interest by visualizing (mental models) its structure and variables (level & rates) that are or could influence the system’s behaviour and then formulating policies that would help improve the overall system’s behaviour over the desired time horizon.

According to Jay Forrester (father of system dynamics), there are only and only two variables in a system, namely levels and rates. These define how the system behaves over time.

The goal of system dynamics is to

1. Interpret systemic behaviours
2. Design policies to improving the behaviours

Here policy means the rules of how decisions are made within the system. This not only includes looking at the numerical data within the system but also the traditions, values, culture and individual experiences that lead to decision making which results in a certain systemic behaviour.

System Dynamics is applicable not such to physical system (e.g. healthcare system) but also to social system (e.g. patient’s quality of life).