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 based on repeatedly asking the question “why?” until the root cause of a problem is determined. Anecdotally, it takes five “why?” questions to get to the bottom of any problem.
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 well 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 simply when a problem is encountered. In each of these situations, 5 Whys can be used to get to the root cause of what is happening.
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.
5 Whys in practice
Example Let’s consider 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 the 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 grill’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.
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?
How to use 5 Whys?
Translating the above example, try following these steps to effectively use the 5 Whys technique:
Step 1. Bring the team together for a meeting
A 5 Whys exercise needs 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. And for complex issues, be sure to make it clear who is leading the analysis and who makes final decisions.
Step 2. State the problem
When defining the problem, make sure all involved do understand the problem, are not mistaking causes with symptoms. Be precise in all questions and answers.
Step 3. Ask “why” as many times as necessary to find the root cause
Be sure to focus on cold facts, not assumptions, and leave the blame game out of it - be objective and fact-oriented, maintain an atmosphere of trust.
Step 4. Plan a solution
At the end of asking your “whys”, you should have a well-formed problem statement, letting you decide on how to find solutions and assign them to the team.
Step 5. Monitor results
No improvement process is complete without checking up on its results! If need be, all 5 steps can be repeated until you’re satisfied with how the process works.
The 5 Whys helps greatly with establishing a detailed problem statement, letting you find and solve issues, and continuously develop your projects. So, next time you and your team are facing an obstacle, put on your genius cap and think like a kid!