Causal loop diagram

A causal loop diagram is a convenient way of representing the principal feedback loops and related causal relationships relevant to a particular problem situation, without distinguishing between the nature of the interconnected variables. Causal loop diagrams serve as preliminary sketches of causal hypotheses. Later, they enable the essential components and interrelationships to be summarised. Arrows are used to indicate direction of causal influences. Signs (+ or -) adjacent to the arrows indicate polarity: how a change in the variable at the tail of an arrow will produce a change at its head. Fundamentals of causal loop diagrams are described by Goodman (1989). For a detailed explanation, see Sterman (2000: 137-190); for an examination of problems in their use, see Richardson (1986). In this book, cognitive mapping, concept mapping, or Soft Systems Methodology are used as analytical devices to investigate a problem situation. Causal loop diagrams or influence diagrams are then used to formulate dynamic hypotheses for further analysis. When used to inform quantitative system dynamics models, causal loop diagrams have an important limitation: they do not force the modeller to distinguish rate variables from the variables that describe the state of the system, namely state variables (stocks, levels, or accumulators). Also see CATWOE, cognitive map, concept map, causality, feedback, and polarity.