3.2) Stocks And Flows In A Bath

A good example and analogy for stocks and flows is the bath. The bath itself is a simple stock variable which accumulates water, and there are two flows: the inflow tap and the outflow plughole.

We would expect the behaviour of such a simple system to be completely intuitive. The connection between the shape of the inflow and outflow and the resulting stock is, however, far more unintuitive than the simplicity of the system would suggest. We will look at three examples to illustrate this.