Table 1 Key elements of a stock and flow diagram
Element | Definition | Example |
|---|---|---|
Stock | Represented as a phrase in a box. An element in a system, either tangible or intangible, that accumulates or depletes over time. | Perceived water taste |
Flow | Represented as a valve connected to the stock with a cloud on the end. The process by which a stock accumulates or depletes over time. | Flows are often labelled, but not in the initial workshop. Changes in perceived water taste (Fig. 2) |
Auxiliary variable | Represented as a phrase without a box around it. An intermediate element of the system used to clarify a connection between two or more flows or the equation underlying a flow. | Health literacy |
Positive causal arrow | Represented as a blue arrow with a plus sign at the end. A causal relationship where the variable at the beginning of the arrow causes the variable at the arrowhead to change in the same direction. | An improvement in town water taste causes an improvement in perceived water taste AND deterioration in town water taste causes deterioration in perceived water taste. |
Negative causal arrow | Represented as a blue arrow with a minus sign at the end. A causal relationship where the variable at the beginning of the arrow causes the variable at the arrowhead to change in the opposite direction. | An increase in health literacy causes a decrease in SSB consumption AND a decrease in health literacy causes an increase in SSB consumption. |
Colour Coding | Colour is often used in models to draw attention to feedback loops and themes. In this project, each main feedback loop was colour coded for visibility. | The feedback loop representing addiction to SSB is coloured red in Fig. 3. |