The Five Whys

Five Whys Explained

The 5 Whys method was originally developed by Toyota Corporation as a core part of their Toyota Production System. The basic concept is that you ask why repeatedly until you get to the single root cause for a problem, typically a missing or broken process or some human behaviour that can be changed for the better. This example illustrates Jeff Bezos using 5 Whys to understand why an amazon worker had hurt themselves on the production line, reproduced below:

Why did the associate damage his thumb? Because his thumb got caught in the conveyor.

Why did his thumb get caught in the conveyor? Because he was chasing his bag, which was on a running conveyor.

Why did he chase his bag? Because he placed his bag on the conveyor, but it then turned-on by surprise

Why was his bag on the conveyor? Because he used the conveyor as a table

In this case the root cause was a missing table, with some indication that safety training is not working as well as it could. This leads to another point, that of proportional investment. In this clip, Harvard Business Review’s Eric Ries explains that 5 Whys is designed to find a cause and effect chain. Instead of only addressing the root cause, the business should invest effort in addressing all causes in the chain. In our example Amazon would provide tables AND improve safety training e.g. don’t run. Reflecting on the realities of business, Ries also posts a word of caution in trying to change too much, recommending a proportional investment as businesses attempt to resolve problems one step at a time rather than all at once. The two major guidelines are: don’t do too much, and don’t do nothing.

Criticisms of the 5 Whys

When used as a root case analysis technique there are a number of criticisms of the 5 Whys:

  • the focus is on a single root cause only
  • there is no guidance on how to ask why, or which root causes are most important
  • users can too easily focus on symptoms or surface details without getting to the real underlying problems
  • answers are different depending on who you ask, making the process hard to repeat

Many of these issues can be addressed by using an Ishikawa Diagram instead, using the framework of questions as a guide. Instead of asking why a car didn’t start we can now ask why the car didn’t start in terms of the people (driver), the process (technique), the equipment (engine) etc.

The 5 Whys Team

Alternatively, we can use a team approach to the 5 Whys, seeking the best answers to focus on at each stage. This might work a bit like this:

  • Step 1: a facilitator states the problem, everyone writes out their own answers to ‘Why” on a post-it note.
  • Step 2: all answers are grouped, duplicates are removed, and a favourite is picked for the next round of ‘Whys’. Note: the concept of a favourite can be whichever cause would have the greatest impact on reducing the problem if solved.
  • Repeat 4 or 5 times.
  • The final cause and effect chain can be shown by linking the selected answers from each step. The group should discuss this, making any changes until everyone can accept the final decision.

Using 5 Whys for Creative Problem Solving

Creative problem solving is a process starting out with understanding the problem and why it needs to be solved, before moving through ideation and idea selection and into implementation. During this process we need to foster a sense of curiosity and a willingness to elaborate; building details, linking concepts, and forming new ideas as our solution space rapidly evolves. The 5 Whys can be a great way to explore the problem, to understand why it needs to be solved, AND start developing a sense of exploration and curiosity. Rather than just take things at face value, we ask ‘Why?’ and ‘What do you mean?’ and ‘How did that happen?’.

Here are some tips for using 5 whys to quickly set a stage for creative problem solving:

  • Know how bad the problem is, so you know how much effort to spend fixing it
  • Foster curiosity and elaboration. Use a team to generate a lot of potential ‘Whys’ and choose their favourite. Keep ALL answers on the wall, you might want to come back to them later
  • When selecting causes, e.g. he was chasing a bag which was on a running conveyor, ask what you should stop doing, what you are not doing (and should start), and the impact in each case. In this example he should stop chasing the bag but the conveyor should probably keep running or production would be slowed down.
  • Keep it moving. This is a quick and dirty tool, it’s meant to give rapid insight into a problem and its causes. It you want a detailed root cause analysis tool use something else and run that session separately to any form of creative response (since it will be run in critical thinking mode)
  • Try asking ‘Why else’ at each stage to stimulate a lot of potential causes. You can also try asking ‘Why did that happen’, ‘why is that a problem’ and why are we/aren’t we doing this’

You can find more tips here , here and here.


4 thoughts on “The Five Whys

  1. The first time I read about this process was in a book call “Kaizen” by Imai. It was one of the books I read frequently (usually once a year) when I was in my ‘incrementalist’ stage of business process consulting.

    1. Sounds like a good read. I hadn’t realised 5 Whys was used so extensively in lean and six sigma typed process improvement. But I like the potential to use a fairly scientific or logical approach to get groups thinking about what they are doing and why. Particularly at the start of a more creative thinking process.

      1. Kaizen or “Continuous Improvements” is a good read if you can find a copy. The book goes through several examples of how they had employee teams perform incremental improvements to gain 2x to 10x gains rather then the ‘western’ use of innovation to create large step improvements.

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