causalloopdiagram

A causal loop diagram (CLD) is a qualitative tool used in system dynamics to visualize how variables in a system influence one another through feedback loops. It focuses on the structure of cause-and-effect relationships rather than numerical values, helping to identify which feedback mechanisms may drive system behavior.

In a CLD, variables are represented as nodes and directed links connect variables to show influence. Each link is labeled with a polarity, typically a plus (+) for a reinforcing or amplifying influence and a minus (−) for a balancing or dampening influence. When following links around a closed path that returns to the starting variable, a loop is formed. The loop is described as reinforcing if the overall effect tends to amplify changes, or balancing if the overall effect tends to stabilize or counteract changes.

Constructing a CLD usually involves identifying key variables, establishing the direction of influence between them, and assigning the appropriate polarity to each link. Practitioners then trace loops to assess potential feedback structures and their likely qualitative impact on system behavior. CLDs are often used as a first step before building quantitative stock-and-flow models.

Uses of CLDs include hypothesis generation, communication among stakeholders, and early exploration of policy or process dynamics in fields such as business, public health, ecology, and engineering. Limitations include their qualitative nature, the absence of time delays and magnitude information, and potential ambiguity in causal direction without supporting data.