stocks and flows diagram

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Stocks and flows is a systems thinking tool at the core of operational thinking. It depicts the structural understanding of a system - the causal structures that produces the observed behavior. It reveals information about the rates of change of system elements and the measures of the variables of the system.

Types of elements --
With stocks and flows there are two kinds of elements in a system. 'Stocks' are elements accumulate over time and can be measured. 'Flows' represent elements that change over time. Flows lead to changes in stock levels while both flows and stock levels can increase or decrease over time. 'Stocks' are sometimes labeled 'accumulators'.

Possible interrelationships between elements of a system include --

  1. A change in one element adds to another element
  2. A change in one element causes the opposite type of change in another element
  3. Proportional change, either reinforcing or balance, between two elements

Insights --
In line with the system characteristics of multidimensionality and emergence, the same structure can produce multiple behaviors and the same behavior can result from different structures.

The nature of the element will not change the structure of a system. On the other hand, the nature of the links, and whether an element is a flow or a level, will change the behavior of the system.

Stocks and flows are the basis for computer modeling of systems behavior.