Interrelationship Diagrams

Identifying Cause and Effect Relationships

Also known as Relations Diagrams

Interrelationship Diagrams - Identifying Cause and Effect Relationships

© iStockphoto

It's often helpful to look at all the stages of the problem.

When you have a problem to solve, it can be useful to identify all of the possible causes, then address each one in turn. This is fine in many situations, but it can also be time-consuming and costly...

In situations where the possible causes are going to be expensive to deal with, it's helpful to use an Interrelationship Diagram, instead. These, simple diagrams, help you to map out the relationships between all possible causes of the problem, so that you can identify the most significant ones and focus on those first.

In this article, we'll look at Interrelationship Diagrams, and we'll explore how you can use them to identify the probable root causes of a problem.

About Interrelationship Diagrams

Interrelationship Diagrams (also known as Relations Diagrams) are simple diagrams that help you find the root causes of a problem, by helping you understand the relationships between all of the issues that you face. The technique is often associated with Six Sigma, but you can use it in many situations.

Once you've created an Interrelationship Diagram, you'll be able to see which issues are fundamental causes of your problem and which are the effects (symptoms) of these causes. You'll also have a good understanding of which causes you need to deal with first, so that you can make best use of your time and resources.

How to Use Interrelationship Diagrams

It's easy and simple to create an Interrelationship Diagram.

You can do this alone or with your team. If you're on your own, all you'll need is a large piece of paper and a pen. If you're with a group, you can use a whiteboard, flipchart, or computer and data projector. You may also find sticky notes helpful.

Step 1: Identify Your Problem

Your first step is to write down the problem that you need to solve. Write this issue at the top of the paper or whiteboard that you're using.


Janet and her team members are trying to analyze why morale in their organization has plummeted. She starts her Interrelationship Diagram by writing this down at the top of a whiteboard.

Step 2: Brainstorm Possible Causes

You now need to brainstorm issues that may be contributing to your central problem. As you identify these, write each one down around the edge of your piece of paper, or write them on a sticky note, so that you can move them around.

Explore using tools such as Brainstorming, Cause and Effect Analysis, Root Cause Analysis, CATWOE, and the 5 Whys to identify as many of the issues related to your problem as possible.


Janet's team members come up with the following issues that they believe might be causing low morale:

  • A recruitment freeze.
  • Falling sales.
  • No training opportunities.
  • No promotion opportunities.
  • Staff under pressure from management.
  • Negative attitudes.
  • Pay freezes.
  • People working long hours.
  • Dreary workspaces.
  • Miscommunication, resulting in rumors.

She adds these to her Interrelationship Diagram, as shown in figure 1 below.

Figure 1 – Step 2 of Janet's Interrelationship Diagram

Interrelationship Diagram Example 1

Step 3: Identify Cause and Effect Relationships

Now, go through each issue and identify whether it is a cause of another issue or an effect (symptom).

Finding This Article Useful?

You can learn another 46 problem-solving skills, like this, by joining the Mind Tools Club.

Join the Mind Tools Club Today!

If it's a cause of another issue, draw an arrow from it and connect it to the issue it affects. If it's an effect of another issue, draw an arrow to it from the other issue.

Go through each issue to make sure that you have analyzed the causes and effects thoroughly.


Janet and her team identify the cause and effect relationships shown in figure 2, below.

Figure 2 – Step 3 of Janet's Interrelationship Diagram

Interrelationship Diagram Example 2


Avoid drawing two-headed arrows – for the purposes of these diagrams, a relationship shouldn't be both a cause and an effect.

Step 4: Identify Causes and Effects

Now, count up the number of arrows going in and going out for each issue.

Issues with the highest number of arrows leading out are likely to be important drivers or root causes of your problem. (You should also pay attention to issues that feed into these.)

Issues with a high number of arrows leading in are probably important outcomes or effects. You should be able to eliminate many of these as you deal with the root causes.


Janet tallies up the arrows for each issue as follows:

Issue Arrows In Arrows Out
Recruitment freeze. 0 4
Falling sales. 5 1
No training opportunities. 0 2
No promotion opportunities. 0 1
Staff under pressure from management. 2 1
Negative attitudes. 8 0
Pay freezes. 0 1
People working long hours. 1 2
Dreary workspace. 0 2
Miscommunication resulting in rumors. 0 2

She can now see that the recruitment freeze is likely the most significant cause of her problem, as this is contributing to four other issues.

Miscommunication, a dreary workspace, and lack of training opportunities are also causes of several issues (without having causes themselves).


If you want to, you can identify the strength of each relationship by using a solid or dotted arrow: solid arrows represent strong relationships, and dotted arrows represent weaker relationships.

Then score each issue appropriately when you tally up the arrows in and out, using, say, 0.5 for a dotted arrow and 1 for a solid arrow.

Step 5: Deal With the Root Causes

Once you've analyzed your Interrelationship Diagram, you can take steps to deal with the root causes of your problem, or you can do further analysis.

When you analyze your diagram, bear in mind that each of the effects that you have identified will have a different bearing on your overall problem. That's why it can be useful to use decision-making tools such as Decision Matrix Analysis, Pareto Analysis, and Force-Field Analysis when deciding which issues to deal with first.

Key Points

Interrelationship Diagrams are useful tools that help you identify the root causes of problems.

There are five steps in using an Interrelationship Diagram:

  1. Define your problem.
  2. Brainstorm possible causes.
  3. Identify cause and effect relationships.
  4. Identify causes and effects.
  5. Deal with the root causes.

It's best to use this technique alongside other problem-solving and decision-making tools.