2.1) Simple Connections

System Dynamics models are often shown in diagrams that use a consistent notation. Relationships between variables are shown as arrows between them where the direction of the arrow indicates the direction of cause and effect and positive or negative influence is indicated:

In the above case, an increase in A will lead to an increase in B, and a decrease in A will lead to a decrease in B.

This simple diagram consisting of three parts – two variables and the connection between them – represents the basic building block of all casual loop diagrams.