Five Whys


What is it?

The five whys technique is a way to better understand the root cause of a problem or incident. It is often used in conjunction with a fishbone diagram in significant adverse event (SAE) analyses.

This technique aims to move beyond the idea of human error and look at the issues within the system that led to an error or incident.

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Why use it?

The five whys helps to understand the root cause of a problem or incident.

Benefits include

  • Reducing the risk of reoccurrence by dealing with the root cause

  • Preventing problems before they occur

  • Gathering information for identifying other issues

  • Increasing awareness of how a system works

  • Can also be used to understand positive events or behaviours that you wish to encourage as it will help to understand the causes as to why something was successful.

How to use it?

As a team or group of key stakeholders, consider a situation, problem or incident. The technique posits the question ‘why did that happen?’ When a response is created, the technique again asks ‘why did that happen?’ in response to the previous answer, not just an unrelated ‘why’ question. The technique continues to ask ‘why?’ until an end point it reached. This often happens after five ‘whys’ but can be upwards of seven or eight levels. It is best used for simple or moderately difficult situations but may also provide useful insights for significantly complex problems.

The technique looks to find problems, not assign blame. Statements should be based on fact, not on assumptions. It is important to consider whether you are noting down symptoms or causes of problems. It is possible that there are multiple causes, each of which can be separately analysed.

The five whys often works well after creating a fishbone diagram.

More information

NES Quality Improvement Zone - for information including templates

IHI – click for information and a video for how five whys works

NHS Improvement - for a guide for how to complete a five whys analysis