Systems Thinking

Systems Thinking is the construction of models, simplified views of reality, intended to promote understanding. Systems Thinking is also presented as an approach for getting beyond cause and effect to the patterns of behavior that surface the cause and effect, and further, for identify the underlying structure responsible for the patterns of behavior. Systems Thinking models are generally developed as Causal Loop Diagrams (CLDs), though there are shortcomings of CLDs. There is a more disciplined approach to developing models which creates clearer, more well defined and structurally sound, models and additionally provides a foundation from which to investigate the dynamic nature of models.

When thinking about a situation not only is it important to consider the elements relevant to the situation, it is also important to consider the interactions between those elements. As it turns out there are only a few basic types of primitives necessary to describe almost all situations, and even fewer valid interactions between them. The following sections present these primitives as well as the interactions between them and some implications of those interactions.

Primitives

There are only four basic types of primitives needed:

1. A primitive representing a quantify of something, which we will refer to as a stock. A good example of this is a bathtub containing water.
2. A primitive representing the movement of something into or out of a stock, which we will call a flow. With the bathtub stock above water can flow in or out.
3. A primitive which represents a value involved in defining some part of an interaction, which we'll refer to as a parameter.
4. A primitive which conveys information about one primitive to another, which we'll call a link.

Interactions

Considering the stock, flow, parameter, and link characteristics there are only a few valid interactions between them.

The content of one stock can flow into another stock. When the source or destination of the flow is not considered relevant to the situation being considered it is represented as a cloud. When you fill a bathtub with water you are generally not concerned with the source of the water.
A link may be used to convey information: from a stock to a parameter, from a parameter to a parameter, from a parameter to a flow, from a flow to a parameter, from a flow to a flow, from a parameter to a stock in order to establish its initial value.

Sample Model

Orders are a flow into Inventory, a stock, causing it to increase. Sales, a flow, moves Finished Goods, a stock, out of the company. Resources and Productivity, parameters, interact in some manner to define Production, a flow, that moves Inventory to Finished Goods. The diagram to the right is a model of this set of interactions.

Summary

• Your questions is probably, "So what?" By using these primitives the models you develop will provide a much clearer perspective of situations than you could arrive at though any other approach. This will become evident in the subsequent sections.

• All you really need to develop these models is a pencil, paper and an eraser; definitely an eraser because of the iterative nature necessary to clarify the thought. Using software to draw diagrams is even better. The above diagrams were done with Simgua and you'll learn why in the next section.

• Employing the rigor associated with mapping out your thoughts using these conventions result in a qualitative perspective. To fully understand the implications of the interactions, how the elements change over time, and produce a quantitative view requires software that will actually bring the interactions in the model to life. While there are numerous software packages that will do this Simgua is an excellent choice. It is extremely powerful though amazingly easy to use and endlessly extendable if you should need. The reasons for its choice will become evident in the following sections.

Internal Links

• Creating a Model
• The First Discipline

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