page_title: System dynamics
section_title: Stock and flow diagrams
hierarchical_section_title: System dynamics / Topics in systems dynamics / Stock and flow diagrams
caption_attribution_description: English: en:Stock and flow diagram of adoption Diagram created by contributor, from article by en:John Sterman (2001) Systems dynamics modeling: tools for learning in a complex world, California management review, Vol 43 no 1, Summer 2001
context_page_description: System dynamics is an approach to understanding the nonlinear behaviour of complex systems over time using stocks, flows, internal feedback loops, table functions and time delays.
context_section_description: Causal loop diagrams aid in visualizing a system's structure and behavior, and analyzing the system qualitatively. To perform a more detailed quantitative analysis, a causal loop diagram is transformed to a stock and flow diagram. A stock and flow model helps in studying and analyzing the system in a quantitative way; such models are usually built and simulated using computer software.
  A stock is the term for any entity that accumulates or depletes over time.  A flow is the rate of change in a stock.
  In our example, there are two stocks: Potential adopters and Adopters.  There is one flow: New adopters.  For every new adopter, the stock of potential adopters declines by one, and the stock of adopters increases by one.
caption: Stock and flow diagram of New product adoption model
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