Interrelationship Diagram
An interrelationship diagram is an analysis tool that allows a team
to systematically identify, analyze, and classify the cause and effect
relationships that exist among all issues. The analysis helps a team
distinguish between issues that serve as drivers and those that are
outcomes.
When should we use an interrelationship diagram?
Use an interrelationship diagram when a team is struggling to understand
the relationship among several issues associated with a process. The
tool can also be useful in identifying root causes, even when objective
data is unavailable. It also:
- encourages team members to think in multiple directions rather
than linearly;
- explores the cause and effect relationships between the issues;
- allows the key issues to emerge through the process rather than
allowing the issues to be forced by a dominant or powerful team member;
and
- allows a team to identify potential cause(s) even when data don’t
exist.
How do we develop an interrelationship diagram?
- Develop the problem statement
Make sure the issue is presented as a complete sentence, is clear
to all team members and agreed upon by them. Write this statement
at the top of a white board or flip chart.
- If using an original statement, create a complete sentence that
is clearly stated and understood, which has been agreed upon by
all team members.
- If using input from other tools that you may have used such as
the affinity diagram, make sure
that the goal under discussion is the same as the agreed upon statement.
- Develop the issues related to the problem
These issues may be the result of a previous activity such as the affinity
diagram or a brainstorming session,
or the team may need to develop them anew.
- Arrange the issues in a circle
Write the on the white board or flipchart. 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. (View
Diagram 1).
Looking for cause/influence relationships between all of the ideas
and draw relationship arrows.
- Choose any of the ideas as a starting point. If all of the
ideas are numbered or lettered, work through them in order.
- An outgoing arrow from an idea indicates that it is the stronger
influence/cause.
For each combination, ask these questions:
- Is there a cause/influence relationship?
- If yes, which direction of cause/influence is stronger?
- Ask the same question for each box starting from A-EF or have ever
many items you have.
- Then start from B and ask the same questions, then C until you have
gone around all your numbers or letters.
- TIP: Draw one-way arrows in the direction of the
stronger cause or influence ONLY. Make a decision on the stronger
direction. Do not draw 2-headed arrows!
- This process must go around the team to get the consensus on the
stronger influence for each letter or numbered idea. After consensus
is drawn the arrow can be drawn.
Tally influence arrows
For each issue, clearly record the number of arrows going in and going
out and select key item for further planning.
Identify drivers and outcomes
Find the item(s) with the highest number of outgoing arrows and the
item(s) with the most incoming arrows.
- Outgoing arrows. A high number of outgoing arrows
indicate an item that is a potential cause or a driver. This is generally
the issue that teams tackle first.
- Incoming arrows. A high number of incoming arrows
indicate an item that is a key outcome. This can become a focus for
planning either as a meaningful measure of overall success or as a
redefinition of the original issue under discussion.
Draw the final ID identifying the key drivers (greatest number of outgoing
arrows) and key outcomes (greatest number of incoming arrows). Then
highlight those boxes. (View
Diagram 2)
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