The “5 Why’s” methodology is one of the most powerful root cause analysis techniques in the Lean management toolbox.

Any team or procedure can encounter unanticipated problems. Problems, however, are only signs of larger problems. Quick problem solving can be a practical approach. However, it does not protect your workflow from repeating mistakes. Your team should focus on identifying the underlying problem and solving it adequately.

5 “Why” Origins.

One component of Toyota’s manufacturing system is the “5 Why’s” approach. This method was a critical component of the lean manufacturing philosophy developed by industrialist and inventor Sakichi Toyoda.

Toyota’s scientific approach is based on asking “why” five times whenever we discover a problem… By repeating “why” five times, the nature of the problem as well as the solution becomes clear.

People with relevant experience should participate in the process of root cause analysis. In their field of expertise, they should be able to provide you with the most useful information on any issue.

The 5 “why’s” step by step.

Form a team.

Assemble a team of employees from several departments. Each representative should understand the process and be aware of the issue. Having a cross-functional team will allow you to hear different points of view. This will help you gather enough data to reach a reasonable conclusion.

Define the problem.

Develop a brief statement of the problem after discussing it with the team. This will help you define the scope of the problem you plan to investigate. This is very important because it can take a long time to study an issue with a broad scope.

Ask 5 Why’s.

Give one member the authority to control the entire process. The facilitator should continue to ask the “Why” question until the team can identify the root cause of the original problem. Instead of depending on subjective ideas, decisions should be supported by factual data and facts. Don’t ask too many “why” questions. The goal is not to get too much implausible advice.

Keep in mind that sometimes there can be more than one underlying reason.

Take Action.

Now is the time to take corrective action after the team has identified the root cause(s). All members should participate in the discussion to select and implement the best solution that will protect your process from repeated problems. One team member should be responsible for implementing the chosen action plan. He or she monitors the entire process after the choice has been made.

The team should meet after a certain period of time to assess whether their activities have had a favorable impact. If not, the procedure should be done again. In the end, the case should be documented and shared throughout the organization. Sharing this knowledge will provide a full picture of the many problems the team may face and how those problems can be solved.

Examples of 5 Reasons Analysis

When you use the 5-cause method, you seek to determine the root of the problem before you solve it. In fact, the five reasons can help you determine the cause of an unforeseen problem. Difficulties that are considered technological problems often turn out to be human and technological problems. That’s why identifying and addressing the root cause is important if you want to prevent iterations of failure.

5 “Why” Example.

Problem: There is water on the floor.

  • Why? A pipe is leaking.
  • Why. There is too much water pressure in the pipe.
  • Why? The control valve is faulty.
  • Why? No one has checked the control valves.
  • Why? Control valves are not part of the maintenance program.

Finding 5 Why’s

The 5 Why method is a quick and effective approach to solving problems. Its main purpose is to identify the exact source of a particular problem by asking a series of “Why” questions.

Using the “5 Why’s” technique, your team can focus on identifying the root causes of any problem. Instead of blaming others, it encourages each team member to make suggestions for continuous improvement. This gives your team the confidence to fix any problem and prevent a repeat failure.