3.1 Influence diagram
Influence diagrams identify the factors (structural features such as people and events) that have direct and indirect influence on a system and its environment. (See the definition of a systems map for an explanation of 'system'.)
Unlike a multiple cause diagram which traces change over time, influence diagrams identify factors with the capacity to influence at any particular point of time. An influence diagram is more like a systems map in providing a snapshot of a situation.
Influence diagrams differentiate between two types of influences: strong influences and weak influences.
Influence diagrams are used to:
- present an overview of areas of activity, groupings of people or other organizational features relevant to the situation or issue under consideration (the system of interest)
- express a broad view of how things are interrelated in the area you are considering
- explore interrelationships, perhaps leading to re-grouping and re-definition of a system and its components.
An influence diagram is particularly useful as a tool for communication − as a means of sharing or exchanging perspectives or views on a particular situation during initial stages of negotiation and collaborative planning.
- Title: describing the factors of influence being represented by the diagram.
- System boundary (optional but recommended).
- Blobs of varying size.
- Arrows, sometimes of different thickness.
- Words labelling blobs.
Conventions and guidelines
An influence diagram is made up of blobs and arrows. The real message of this type of representation emerges from the arrows. The main steps are:
- Define the system of interest.
- Use blobs to represent components (sub-systems).
- Use words to label components.
- Use arrows to denote capacity to influence (not sequences in time).
- Use different line thickness (or colour) to indicate different influence strengths.
- Do not use double-headed arrows. Influences between two components are rarely, if ever, truly reciprocal and of the same type. Where there is thought to be dynamic two-way influences, use two separate arrows pointing in opposite directions.
- Use labels on arrows if the nature of the influence is not obvious from the context.
Activity 3 Animated tutorial 1
Watch the animated tutorial (click on ‘View’) below this paragraph to see how I built up my influence diagrams of the WWP. If you are still a bit unsure about what an influence diagram is you might like to view the optional animation, What is an influence diagram?, before viewing the WWP examples.
Click on WWP Influence diagram to see the description of the animated tutorial.