Interrelationship Diagram
Interrelationship Diagram is a method to identify relationships among a set of items. Items that have a cause or effect associated on another item are linked together (and given weight) for the purpose of identifying the items most affected or items affecting other items the most. Also called "relations diagram."
The tool can also be useful in identifying root causes, even when objective data is unavailable.
When to Use a Relations Diagram
When trying to understand links between ideas or cause–and–effect relationships, such as when trying to identify an area of greatest impact for improvement.
When a complex issue is being analyzed for causes.
When a complex solution is being implemented.
How to Use it
Develop the problem statement.
Make sure the issue is presented as a complete sentence and is clear to all team members. Write this statement at the top of a white board or flip chart.
Develop issues related to the problem.
These issues may be the result of a previous activity such as an affinity diagram or a brainstorming session, or the team may need to develop them now.
Arrange the issues in a circle.
Write the issues on the white board or flip chart. If the issues have already been recorded on sticky notes, arrange them in a circular pattern.
Identify cause-and-effect relationships.
Using any of the issues as a starting point, work through the relationships in sequence. For each pair of issues, determine if there is
no cause/effect relationship,
a weak cause/effect relationship, or
a strong cause/effect relationship.
If the team determines there is a cause/effect relationship, determine which issue is the cause and which is the result.
Draw arrows to indicate directions of influence.
For each relationship pair, draw an arrow from the issue that is the cause to the issue that is influenced. For strong relationships, use a solid line. For weaker relationship, draw a dashed line. Although some relationships may seem evenly balanced, always determine which is the stronger influence and draw the arrow in that direction. Never draw two-headed arrows.
Tally influence arrows.
For each issue, clearly record the number of arrows going in and going out.
Identify drivers and outcomes.
A high number of outgoing arrows indicates that an issue is a driver or possible root cause. The team generally evaluates these issues first to gain the most farreaching results. A high number of incoming arrows indicates that an issue is an outcome. These issues may serve as important measures of success
