Quality Improvement Zone

A cause and effect diagram is a visual tool that helps teams explore the factors contributing to a problem. By organising possible causes into categories, it supports a structured discussion about what may be driving the problem and where improvement efforts could be focused. They help bring together different perspectives and encourage teams to look beyond symptoms to identify possible underlying causes.

A cause and effect diagram typically includes:

• A clearly defined problem statement that describes the issue without assuming a cause
• Major cause categories that group related contributing factors, such as people, processes, equipment, materials, environment or policies
• Possible causes that may be contributing to the problem
• Sub-causes identified through further exploration and discussion

A cause and effect diagram is sometimes called a fishbone diagram because of its appearance, or an Ishikawa diagram after its creator.

Cause and effect diagrams help teams move beyond assumptions and develop a deeper understanding of a problem. By exploring possible contributing factors in a structured way, teams can identify areas for further investigation and generate ideas for improvement.

Cause and effect diagrams can help you:

• develop a shared understanding of a problem
• identify possible contributing factors that may otherwise be overlooked
• encourage discussion based on evidence rather than assumptions
• explore potential sub-causes of a problem
• identify opportunities for improvement and generate change ideas
• support the development of improvement plans and driver diagrams

A cause and effect diagram helps identify possible causes and areas for further investigation. It does not confirm that a particular factor is responsible for the problem. Additional evidence may be needed to understand which factors are having the greatest influence.

Cause and effect diagrams work best as a collaborative exercise involving people with different perspectives and knowledge of the problem. The aim is to explore possible causes using evidence and experience, rather than jumping straight to solutions.

A cause and effect diagram template can be downloaded below. You can also start by using flip chart paper with sticky notes or an online whiteboard.

1. Define the problem

Develop and agree a clear problem statement, avoiding wording that assumes a particular cause.

2. Gather evidence

Before starting, gather information about the problem. This might include data, observations, feedback or other sources of evidence. Wherever possible, go to where the problem occurs and seek facts rather than relying solely on opinion.

3. Brainstorm possible causes

Work together to identify all the factors that may be contributing to the problem. Record each idea, encouraging everyone to share.

4. Identify cause categories

Agree the major categories by sorting the causes into groups. Common categories include people, processes, equipment, materials and environment, although categories can be adapted to suit the problem being explored.

5. Explore sub-causes

For each possible cause, ask "Why?" repeatedly to explore what may be contributing to the issue. Techniques such as 5 Whys can help teams move beyond symptoms and identify potential sub-causes. Where there is disagreement, seek additional evidence before drawing conclusions.

6. Review and validate the diagram

Review the completed diagram with the team to ensure it accurately reflects the available evidence and the different perspectives represented. Consider whether any important causes may have been missed and where further investigation may be needed.

7. Use your findings to inform improvement

Use the completed diagram to identify priorities for further investigation and opportunities for improvement. The insights gained can help teams generate change ideas, develop driver diagrams and decide what to test through PDSA cycles.