Stock and flow (or Level and Rate) diagrams are ways of representing the structure of a system with more detailed information than is shown in a causal loop diagram. Stocks (Levels) are fundamental to generating behavior in a system; flows (Rates) cause stocks to change. Stock and flow diagrams are the most common first step in building a simulation model because they help define types of variables that are important in causing behavior. We will construct a diagram describing the relationships among awareness of a product and the number of customers and potential customers.
A completed example of the model is provided for reference; see customer.mdl located in the directory UserGuide\chap05\Complete.
