How to Use the 5 Whys Tool to Conduct Root Cause Analysis

Root cause Analysis is a well-structured, systematic approach focused on uncovering the true cause of a problem and consequently, how to address it.

Root Cause Analysis should be systematic and documented, providing evidence of the results and conclusions.

Benefits of Root Cause Analysis

The next step, after identifying the root cause, is to develop a detailed Action Plan. This plan should clearly specify the activities to be conducted, assign responsibilities, set deadlines, and define monitoring methods. This strategy ensures the effective elimination of the underlying cause and prevents the recurrence of the problem.

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Case of an unexpected machine interruption:

  • Question 1: What caused the machine’s sudden interruption?
    • Answer 1: The fuse burned out due to a machine overload.
  • Question 2: What led to the machine overload?
    • Answer 2: The overload was caused by insufficient oil in the transmission shaft.
  • Question 3: Why was there insufficient oil in the shaft?
    • Answer 3: The lubrication pump wasn’t distributing enough oil to the transmission shaft.
  • Question 4: Why wasn’t the lubrication pump circulating enough oil?
    • Answer 4: The pump was clogged with metal shavings.
  • Question 5: Why was the pump clogged with metal shavings?
    • Answer 5: Because the pump lacks a filter.

Thus, the absence of a filter in the pump, leading to shavings clogging it, resulted in an overload of the fuse, ultimately causing the machine to stop. In this example, each situation triggers a subsequent effect, underscoring the importance of addressing the fifth cause or “why” to solve the root problem.

Often, due to the urgency of finding solutions within deadlines, there is a tendency to work hastily, without a proper analysis of the problem. This approach addresses the symptoms rather than the root causes. There is not only the risk of the undesirable situation recurring but also of expending time and resources again on the same problem. Thus, quick solutions generally imply greater resource use and fail to eliminate the problem. Therefore, effective identification of a problem’s root cause benefits companies by resolving issues effectively and using resources more efficiently.

Objective of Root Cause Analysis

This is a simple yet effective technique where the root cause of a problem is identified through a series of questions and answers. The principle of this methodology is that by asking 5 questions, it is possible to establish an adequate understanding of the problem’s cause. The answer to one question leads to another question, and so on until the cause of the problem is reached. It may not always be necessary to ask five questions; depending on the problem, the cause can be known on the 3rd or 4th question, or more than five questions may be required. Generally, the answer to the fifth question reveals the cause of the problem.

For corrective and/or preventive actions to effectively improve company operations, a systematic and efficient tool is necessary for resolving the problems that emerge. The most crucial part of this methodology is the accurate identification of the causes that lead to these problems. In this article, we discuss the importance of correctly identifying a problem’s root cause, with a focus on the “5 Whys” technique, one of the various methods for conducting root cause analysis.

Steps to Resolve a Problem

  1. Precisely identify and define the problem.
  2. Collect data and other evidence related to the problem.
  3. Identify possible conditions contributing to the problem.
  4. Identify and integrate the roles/positions involved in solving the problem.
  5. Analyze the root cause of the problem.
  6. Develop recommendations and actions to address the problem.
  7. Implement the recommendations and actions.
  8. Verify that the implemented solutions have effectively resolved the problem.

What is Root Cause Analysis?

The technique was initially developed by Sakichi Toyoda and later adopted by Toyota Motor Corporation during the evolution of its manufacturing methods. It is a critical component of problem-solving training within the Toyota production system. Taiichi Ohno, the architect of the Toyota production system, describes the 5 Whys methodology as “…the basis of Toyota’s scientific approach…by repeating ‘why?’ five times, the nature of the problem, as well as its solution, becomes clearer.” The tool has seen widespread use beyond Toyota and is now also employed within Six Sigma methodologies.

Example of Applying the “5 Whys” Methodology

Organizations often analyze the consequences of an undesirable situation, so a methodology to identify and analyze the causes of problems, solve them, and more critically, prevent their recurrence, is essential. This process allows Senior Management to efficiently use resources and improve activities.

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The purpose of identifying the root cause of a problem is to determine:

  1. What happened?
  2. Why did it happen?
  3. How can we prevent it from happening again?

The key to this technique is to foster a logical approach to problem-solving, avoiding assumptions and following the direct chain of causality. As mentioned in the steps to resolve a problem, it is crucial to identify the roles related to the undesirable situation, ensuring the technique’s effectiveness and the implementation of systematic actions to prevent its recurrence.

Brief History of the 5 Whys Methodology

Often, an undesirable situation results from several factors, such as infrastructure conditions, human or process failures, inadequate methods, lack of resources, etc. Therefore, several root causes can usually be identified.

A critical element in a management system is continuous improvement. Among the fundamental components of this improvement is the implementation of corrective and/or preventive actions. These actions help address undesirable situations, either actual or potential, within an organization. Such situations may arise from:

  1. Internal or external audits
  2. Customer complaints or claims
  3. Results of management reviews
  4. Improvement areas identified by employees

One tool for problem-solving, the Ishikawa or Fishbone Diagram, is based on this premise, identifying various factors that could cause a problem or undesirable condition.

Methodology of the “5 Whys”

In this article, Pro QC International provides a detailed explanation of a key tool: the “5 Whys”. How did it originate? What is its fundamental role in problem analysis and process improvement?