Prototyping an analog computing representation of predator prey dynamics

Analyzing systems can be a complex task especially when there is feedback across several variables in the model. Formal mathematical notation makes it difficult to understand the influences of feedback and cause/effect. Forrester created the System Dynamics methodology as a means to assist in this understanding by employing a hydraulic analogy. In this methodology, variables become simulated objects such as water valves or tanks. A variety of implementations allow users to construct and simulate these models. The problem is that for many implementations, the intuitive nature of water flow, intended by the methodology, is not as clear as it could be. For instance, the rate of flow or level in a tank may not be visualized. For novices, we suggest that this issue, as well the ability to understand relationships and linking across multiple representations can be problematic. We designed and describe a web-based interface that solves these problems.