Flow Diagrams

Systems diagrams and flow diagrams usually represent a sequence of events, often indicating cause and effect. Flow diagram line models are used to represent the ways systems work within organizations, and they can provide good visual images of what may be complex processes.

For example, the control loop model shows a typical pattern of production, measurement, correction. The usual simple metaphor is of a thermostat in a heating system, which assesses the temperature against a standard and sends messages to the boiler to adjust the actual temperature if necessary.

In complex systems these diagrams can help by focusing attention on the most important aspects of the system. In the context of a particular control system, we can question every component: is the standard correct? is the tolerance too wide or too narrow? are we checking the sample at the right times? is the sample too large/too small? is the information about variations being received accurately? at the right time? is corrective action carried out as quickly as possible? and so on.