5 whys

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The 5 Whys is a simple tool that helps teams explore the factors contributing to a problem.

What is it?

By repeatedly asking "Why?", teams can move beyond symptoms and assumptions to develop a deeper understanding of the system and the conditions that allow a problem to occur.

Despite its name, the goal is not necessarily to ask "Why?" exactly five times. Some issues may need fewer questions, while others may require more.

Most problems are influenced by multiple interacting factors rather than a single root cause. The purpose of 5 Whys is not to find one answer, but to help teams understand the different conditions, processes and system factors that contribute to a problem.

The tool works best when teams remain curious, avoid assumptions and use evidence wherever possible to support their thinking.

What does this tool look like?
The image shows a simple diagram representing the Five Whys method. There are five blue rectangular boxes arranged diagonally in a descending staircase pattern from top left to bottom right. Each box contains the text: Why? A downward-pointing arrow appears between each box, indicating progression from one "Why?" question to the next.
Why use this tool?

The 5 Whys helps teams move beyond surface-level explanations and explore the factors contributing to a problem. It encourages deeper thinking about how systems, processes, people and conditions interact.

Using 5 Whys can help you:

  • explore the factors contributing to a problem
  • move beyond symptoms and assumptions
  • encourage curiosity and deeper investigation
  • develop a shared understanding of how the system contributes to a problem
  • identify opportunities for improvement and change
  • communicate the team's thinking in a simple visual format 

The goal of 5 Whys is not to identify a single person, event or root cause. Most problems arise from a combination of factors within a system. The tool helps teams explore these factors and understand how they contribute to the problem.

Where does this tool fit in the improvement journey?

This tool is relevant at this stage of the quality improvement journey.

This tool is relevant at these stages of the quality improvement journey.

How to use it

The 5 Whys works best as a collaborative exercise involving people with different perspectives and knowledge of the system. The aim is to explore possible contributing factors rather than jump straight to solutions.

1. Define the problem

Start by clearly describing the problem you want to understand. Where possible, use data to help define the issue and avoid wording that assumes a particular cause. Writing the problem down helps everyone focus on the same issue.

2. Ask why the problem occurs

Ask the team why they think the problem is happening and record the responses. Encourage people to share observations, evidence and different perspectives.

3. Continue exploring

For each response, ask "Why?" again. Continue exploring the factors behind each answer rather than accepting the first explanation. Some lines of enquiry may require more questions than others.

4. Look for contributing factors

As the discussion develops, explore how different factors may interact. Problems are often influenced by multiple conditions, processes or behaviours rather than a single cause.

5. Group related themes

Some of the "Whys" may relate to the same underlying issues. Grouping similar responses can help identify common themes and patterns across the system.

6. Use evidence to challenge assumptions

Where there is uncertainty or disagreement, seek additional information rather than relying solely on opinions. The purpose is to understand the system more accurately, not to prove a particular explanation.

7. Identify opportunities for improvement

Use what you have learned to identify potential changes that could influence one or more of the contributing factors. These insights help generate change ideas and inform improvement planning.

Using 5 Whys alongside other tools

The 5 Whys is often effective when used alongside a cause-and-effect diagram. A cause-and-effect diagram helps identify contributing factors, while 5 Whys can be used to explore those factors in greater depth.

For example:

A cause-and-effect diagram may identify issues relating to people, processes, equipment and environment.

5 Whys can then be used to explore each of these areas in more detail.

The insights gained can help generate change ideas and inform driver diagrams, improvement plans and PDSA testing.