When something goes wrong, people always want to know why. Why did this happen? Why did this go wrong? It’s a logical question, but stopping there is likely to lead to a dead end.
To get at the core of why the unexpected event or challenge happened, you need to dig deeper. Instead of stopping at one, you need to ask why five times.
The 5 Whys
The core idea of the 5 Whys system is exactly what it sounds like: ask the question “Why?” five times to understand the root cause of an issue. It was developed by Taiichi Ohno, the father of the Toyota Production System. “Observe the production floor without preconceptions,” he advised his staff. “Ask ‘why’ five times about every matter.”
Ohno used a malfunctioning welding robot as an example:
- “Why did the robot stop?”
The circuit has overloaded, causing a fuse to blow.
- “Why is the circuit overloaded?”
There was insufficient lubrication on the bearings, so they locked up.
- “Why was there insufficient lubrication on the bearings?”
The oil pump on the robot is not circulating sufficient oil.
- “Why is the pump not circulating sufficient oil?”
The pump intake is clogged with metal shavings.
- “Why is the intake clogged with metal shavings?”
Because there is no filter on the pump.
If the questions had stopped at the first or second why, it would be tempting to think the problem could be solved with a new fuse or pump. But, the problem would have reoccured in a few months. In this case, the issue was caused by human error. Someone had forgotten to attach a filter to the pump.
By asking and answering “Why?” five times, you can drill down to the core issue, which is often hidden behind symptoms. “The root cause of any problem is the key to a lasting solution,” Ohno said.
When to Use the 5 Whys
The 5 Whys system is most effective when used to solve simple to moderately challenging issues. If you’re using 5 Whys for complex issues, you need to be more careful. With complex problems, there are often multiple causes. Using the 5 Whys could lead you down a single path, causing you to ignore the other underlying issues.
Because the 5 Whys is relatively easy, it can be a great tool for kicking off brainstorming around a problem before you take a more in-depth approach.
A Few Limitations to Keep in Mind
The 5 Whys method does have some limitations.
- The person leading the 5 Whys must have expert knowledge about the problem and possible issues. If the cause is unknown to the person doing the problem-solving, the method may not lead to the true cause. In the earlier example, it’s unlikely that someone with zero mechanical knowledge would have noticed the missing filter on the pump intake.
- The success of the method relies on the skill of the facilitator. One wrong answer may completely throw off the questioning, leading to a wrong conclusion.
- An assumption of the 5 Whys method is that there is that presenting symptoms all stem from one cause. For complex problems, this isn’t always the case. A 5 Whys analysis may not reveal all of the causes that are tied to these symptoms.
How the Process Works
Ready to try it? The 5 Whys method follows a very simple five-step process.
1. Assemble your team.
First, invite people who are familiar with the issue and the process you are trying to fix to the 5 Whys meeting.
2. Select a facilitator for your meeting.
The facilitator will lead the discussion, ask the 5 Whys, and keep the team focused on the issue at-hand.
3. Define the problem.
Discuss the problem with your team, and then focus on creating a clear and concise problem statement. To get started, answer the questions, What is going on, when did it happen, where did it happen, and who found the problem.
Write your problem statement on a whiteboard, leaving enough room to answer the 5 Whys below.
4. Ask why five times.
The first why should cover why the problem is happening. The method will work best if your answer is grounded in fact. No guessing allowed. Avoid going down the path of deductive reasoning, which can muddy the process. Answer each question quickly to avoid going down rabbit holes and jumping to conclusions.
Continue asking why until you feel that you’ve examined each path and can go no further. If your first why generated more than one reason, you can now go back and repeat the process until you’ve explored those routes, as well.
Note: As you go through this process, you may find that someone dropped the ball along the way. Instead of placing blame, the goal is to ask, Why did the process fail? This line of questioning will show what organizational processes need to be fixed.
5. Address the root causes.
By now, you should have identified one true root cause. With the group, discuss what countermeasures can be taken to prevent the issue from happening again. The facilitator may assign responsibilities for these countermeasures to the group.
6. Monitor your countermeasures.
The process doesn’t end there.
It’s important to monitor how effectively your measures solved or minimized the problem. If nothing has changed, you may have identified the wrong root cause and need to repeat the process.
That’s it! While the 5 Whys method was originally developed for use in a manufacturing setting, it can be beneficial in a wide range of applications. Do you use the 5 Whys in your work or personal life? If so, how was the method worked for you?