Purpose: To identify cause-effect or method-objective relationships among related items in a system when the interactions are complex or involved.
The relationship diagram, in contrast to the affinity diagram which only shows logical groupings, helps map the logical relationships between the related items uncovered in the affinity diagram. The relationship diagram shows cause and effect relationships among many key elements. It can be used to identify the causes of problems or to work backward from a desired outcome to identify all of the causal factors that would need to exist to ensure the achievement of an outcome.
The key factors affecting the main drivers can then be examined using the tree diagram.
- State the problem or issue under discussion--software defects, customer retention, process steps, whatever. Write this on a Post-it ® note.
- the key issue at the center of a white board or on one side or the other.
- Generate cause-effect issues by brainstorming or by using the notes generated for the affinity diagram (except the header notes) and arrange them according to cause-effect. (Note: There should be more than nine and less than fifty notes when completed, otherwise the problem is either too simple or too complex for this method.)
- Draw one-way arrows to indicate the cause-effect relationship among all of the components of the diagram. Avoid two way arrows; decide which component has the most influence and draw the arrow in one direction only.
- Identify the key issues (ones with the most arrows coming out of them) with darker lines or other shading.