The 5 Whys Technique

The 5 Whys Technique

The 5 Whys is a brainstorming technique used in Lean. It was developed by the founder of Toyota - Sakichi Toyoda, and it’s a tool allowing to determine the root cause of a problem by asking “why?” at different levels of an explanation.

Although it is referred to as 5 Whys there is no magic in the number 5, certain problems will be solved with fewer than 5 or more than 5 questions. The goal is simply to ensure that the team has understood the problem as much as possible. Once the root cause is found, a correct solution will be easier to establish.

The wisdom of children and geniuses

It’s been said that if Albert Einstein had an hour to solve a problem, he would spend the first 55 minutes figuring out the proper question to ask. The 5 Whys technique is aligned with this kind of thinking. Young children naturally ask why? - they instinctively know that this is the way they’ll get to the truth. And while it often exasperates adults, who finally give in and say “because I said so”, this truly is a genius technique of getting answers.

When and where to use 5 Whys

The technique can be used while doing Gemba, when the team is mapping the value stream and discover an activity that constitutes a waste, or when any problem is encountered. In each of these situations 5 Whys can be used to get to the root cause of what is taking place.

The 5 Whys technique can also work in group settings through the use of boards or flip charts. The team can start with their original question and follow the trail to the source by asking why at the start of each explanation.

How to use 5 Whys - example

Let’s consider an example of how a restaurant can use the 5 Whys to get to the bottom of a problem. The restaurant owner finds customers stating they are not satisfied with their food. The problem is being reported by the cashier at the front desk, after the customers have paid their bills.

So, the owner calls in everyone - the front desk staff, the kitchen staff and the waiters, and on their whiteboard he writes down in large font: Why do we have unhappy customers?
The owner then starts going around the room and first asks the cashier: Why do you think we have unhappy customers? The cashier says: we don’t have unhappy customers in general, only some customers are unhappy. The owner then re-asks the question: Why are some customers unhappy? The cashier explains that a portion of the customers are unhappy with the temperature their steaks are being served at.

The owner then asks the waiters: Why are steaks being served at the wrong temperature? The waiter explains that it’s only since last Wednesday, that some customers have started complaining that their steaks are not warm and slightly underdone.

The owner then asks the grillers: Why since last Wednesday are some steaks served not warm enough? The chef explains that on Wednesday they’ve intermittently started to cook some steaks on a brand new grill.

At that, the restaurant owner stops the meeting and they all go to inspect the grill. It is found that the griller’s temperature gauge is not working and that it’s set to 10 degrees lower than normal. The team has likely come to the root cause of unhappy customers.

The key things to take from our example:

  1. The restaurant owner gathered everyone that could provide him with information. It is important for a 5 Whys exercise to gather as many of the subject matter experts as possible. But likewise - there’s no point in involving people that know nothing about the problem.
  2. The owner never accused anyone. This was not a blame game exercise, the owner wanted to find out what was happening, not whom to blame and punish.
  3. The owner asked “why..?” questions to each answer he got.
  4. At the end, the owner had a well-formed problem statement.
    5 Whys is a tool that you can use to solve any problems and develop your projects. Let’s compare the first question that was asked in the example:
    “Why do we have unhappy customers?”
    with the detailed question that became possible to pose at the end of it:
    “Why, since Wednesday, have some of our customers been unhappy with the temperature of their steaks?”

The 5 Whys helps greatly with establishing a detailed problem statement. So, next time you and your team are facing a problem, put on your genius cap and think like a kid!