Digital & Computing

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Systems diagramming

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# 4.3 Diagrams for connectivity

Relationship diagrams offer one way of putting more order into your understanding of a situation. Each element of a situation is named in an oval and lines between ovals indicate that there are relationships between the particular elements – but no more than this!

Systems maps are another way of developing one's understanding of a situation. Systems maps are essentially ‘structure’ diagrams. Each element or sub-system is contained in a circle or oval and a line is drawn round a group of elements or sub-systems to show that the things outside the line are part of the environment while those inside the line are part of the system. There are NO lines connecting elements, sub-systems or systems in a systems map; it is purely a statement of the structure as you see it in your mind.

Influence diagrams are developed from systems maps and indicate where one element in the situation has some influence over another. Arrows indicate the direction of the influence and the lines between elements may be of different thickness, shading or colour in order to distinguish strong and weak influence. Strictly speaking, influence should only be shown from elements at a higher or at the same level in the system; that is to say, subsystems cannot influence systems and sub-systems and systems cannot influence the environment – but some people do not follow this convention.

Where a clear pattern of cause and effect can be discerned in a situation, the causal loop and multiple cause diagrams may be useful in describing the interactions between different elements in a situation. By convention, multiple cause diagrams have the elements laid out, without ovals or any other sort of enclosure, in whatever way assists in clarifying the processes. Elements are joined by arrows indicating where there is a causal relationship between the elements. Where there is cause and effect in both directions between two elements, separate arrows indicate this.