5 Whys: How to Uncover Root Causes [Examples]

The Five Whys technique is a simple and effective tool for identifying the root cause of an issue. It involves asking “why” repeatedly (up to five times) to dig deeper into the underlying causes of a problem and to uncover the chain of events leading up to it. Developed by Sakichi Toyoda, the founder of Toyota Industries, this approach has become an essential part of problem-solving and continuous improvement in various industries.

By asking “why” multiple times, the Five Whys method helps us avoid settling for surface-level explanations, which can often hide the true causes of a problem. This technique promotes a culture of curiosity and encourages teams to collaboratively explore all possible answers until the core issue becomes evident. In turn, this allows for the development of effective and targeted solutions, resulting in long-lasting improvements rather than temporary fixes.

For example, consider a scenario where the production line in a factory has slowed down significantly. By employing the Five Whys technique, the team might discover that faulty machinery is the immediate issue (first “why”). Further investigation might reveal a lack of maintenance as the cause (second “why”). After a few more iterations, the team might uncover a gap in training for maintenance workers (fifth “why”) as the root cause, which can then be addressed by implementing a comprehensive training program.

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History of Five Whys

The Five Whys technique has its roots in the Toyota Production System, developed by Sakichi Toyoda, the founder of Toyota Motor Corporation. Sakichi believed that by asking “Why?” repeatedly, one could identify the core of any problem and develop effective solutions. This approach was later refined and promoted by Taiichi Ohno, known as the father of the Toyota Production System.

In its early days, the Five Whys method was adopted by Toyota to improve its manufacturing processes and eliminate waste, contributing significantly to the company’s global success. By implementing this simple yet powerful approach, Toyota was able to identify root causes of recurring issues and develop long-term, sustainable solutions.

Over time, the Five Whys technique has gained popularity beyond its use within the automotive industry. Today, it is employed in various fields and organizations as a valuable problem-solving tool. Its effectiveness stems from its simplicity, allowing individuals and teams to quickly identify, understand, and address the underlying causes of an issue, rather than merely treating the symptoms.

Here are some examples of the Five Whys in action:

  1. Example: A production line stops unexpectedly.
  • Why did the line stop? The machine overheated.
  • Why did the machine overheat? The coolant pump failed.
  • Why did the coolant pump fail? It was not maintained properly.
  • Why was it not maintained properly? There was no scheduled maintenance plan.
  • Why was there no maintenance plan? The necessity of regular maintenance was not recognized.
  1. Example: A digital marketing campaign fails to generate leads.
  • Why didn’t the campaign generate leads? The target audience didn’t engage with the ads.
  • Why didn’t the target audience engage with the ads? The ad creative was not compelling.
  • Why wasn’t the ad creative compelling? It didn’t resonate with the audience’s interests.
  • Why didn’t it resonate with the audience’s interests? Market research was not conducted.
  • Why wasn’t market research conducted? The project timeline was too tight.
  1. Example: A software application experiences frequent crashes.
  • Why does the application crash? There are several bugs in the code.
  • Why are there bugs in the code? The testing process was inadequate.
  • Why was the testing process inadequate? The test cases were not comprehensive.
  • Why were the test cases not comprehensive? The testing team was understaffed.
  • Why was the testing team understaffed? The importance of thorough testing was not prioritized.
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Understanding the Five Whys Process

Root Cause Analysis

The Five Whys process is a practical approach to root cause analysis. Its primary goal is to identify the underlying cause of a problem, rather than fixing it temporarily. By asking “why” repeatedly, a team can delve deeper into the issue and assess the contributing factors. This scientific approach to problem-solving enables a team to address the root cause and prevent the problem from recurring.

The process begins by stating the problem, followed by asking “why” the problem exists. Each successive answer becomes the subject of the next “why” question until the root cause is identified. Typically, five questions are sufficient, although more or fewer may be necessary depending on the situation. The Five Whys process encourages open communication and collaboration among team members in order to effectively solve problems.

Iterative Interrogative Technique

The iterative interrogative technique in the Five Whys process promotes continuous improvement by emphasizing critical thinking. It helps team members to approach problem-solving with a clear mindset, focusing on the reasons for the problem instead of quick fixes. Continuous improvement is vital for maintaining a high level of performance in any organization.

Throughout the process, team members should be encouraged to ask questions and contribute their perspectives. This dialogue fosters a culture of learning and improvement where everyone’s input is valued. Note that it is essential to keep an open mind and focus on facts rather than assumptions when seeking the root cause of a problem.

Example 1:
  • Problem: Customer complaints about long wait times
    • Why? There are not enough customer service representatives
      • Why? Budget constraints limit the number of staff members
        • Why? Revenue has decreased, affecting the budget
          • Root cause: The organization needs to find ways to increase revenue to hire more staff and reduce wait times for customers.
Example 2:
  • Problem: Frequent machine breakdowns in production
    • Why? Machine maintenance is not performed regularly
      • Why? The maintenance schedule is unclear
        • Why? The maintenance team is overworked and disorganized
          • Root cause: Implement a clear maintenance schedule and provide additional support for the maintenance team to prevent machine breakdowns.
Example 3:
  • Problem: Project deadlines are consistently missed
    • Why? Tasks take longer than expected to complete
      • Why? Team members are unsure of their roles and responsibilities
        • Why? There is a lack of clear communication and project management
          • Root cause: Improve project management and communication to ensure that deadlines are met.

Five Whys in Decision-Making

The Five Whys technique is a simple and effective tool in decision-making, helping identify the root causes of problems to reach a more informed decision. By asking “Why?” five times, it leads to deeper levels of understanding. This approach can enhance decision-making processes by promoting a systematic method to explore underlying issues.

Using the Five Whys technique in decision-making enables a more comprehensive analysis by encouraging reflection on multiple facets of an issue. It highlights the value of understanding the root causes before finalizing decisions, which can result in more informed and deliberate choices.

The benefits of using the Five Whys in decision-making include better allocation of resources, enhanced problem-solving skills, and more sustainable solutions to challenges. Through this method, decision-makers can effectively address recurring problems, reducing the likelihood of similar issues in the future.

Example 1: A project is continually behind schedule, which impacts profitability.

  1. Why is the project behind schedule? The team is constantly missing deadlines.
  2. Why is the team missing deadlines? They are struggling with workload prioritization.
  3. Why are they struggling with workload prioritization? There is a lack of clear project milestones.
  4. Why are there no clear project milestones? The project manager lacks experience in defining them.
  5. Why does the project manager lack experience? They were promoted without proper training. Decision: Implement project management training for the project manager and establish clear milestones for the team to follow.
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Example 2: Customer complaints have increased in recent months, affecting brand reputation.

  1. Why have customer complaints increased? Wait times for service have increased.
  2. Why have wait times increased? There is a shortage of staff during peak hours.
  3. Why is there a staff shortage during peak hours? Current scheduling does not account for demand fluctuations.
  4. Why doesn’t scheduling account for demand fluctuations? The scheduling system is outdated and inefficient.
  5. Why is the scheduling system outdated and inefficient? There has been a lack of investment in technology. Decision: Invest in a new scheduling system to improve staff allocation during peak hours, reducing wait times and enhancing customer satisfaction.

Example 3: Product defects have led to a decline in sales and an increase in returns.

  1. Why are there product defects? Quality control measures are insufficient.
  2. Why are quality control measures insufficient? The current procedures are not comprehensive enough.
  3. Why aren’t the procedures comprehensive enough? There’s no dedicated quality control team.
  4. Why is there no dedicated quality control team? The company hasn’t prioritized quality management.
  5. Why hasn’t the company prioritized quality management? The focus has been on cost reduction instead. Decision: Allocate resources to establish a dedicated quality control team and implement more robust procedures to address product defects and ensure customer satisfaction.

The Role of Five Whys in Process Improvement

The Five Whys technique is an essential tool for effective process improvement in various industries. Primarily used in Lean Manufacturing, Six Sigma, and Kaizen methodologies, it helps to identify root causes of problems and fosters continuous and quality improvement. The purpose of Five Whys is to prevent issues from recurring and make informed decisions for sustainable enhancements in performance.

When implementing continuous improvement practices, it is crucial to understand that issues often have deeper underlying causes than what appears on the surface. The Five Whys method encourages identifying these causes through an iterative, question-based process to reveal the true origin of the problem.

A common application of Five Whys is in quality improvement initiatives, where the technique ensures that improvements focus on addressing the root cause of a defect rather than just the symptoms. This fundamental approach helps organizations eliminate waste and inefficiencies in their processes and systems.


In conclusion, here are a few examples of how the Five Whys technique can empower various process improvement methodologies:

  1. Troubleshooting machinery issues in a manufacturing facility allows for targeting maintenance protocols, reducing downtime.
  2. In a Six Sigma setting, applying the Five Whys method on a defective product leads to identifying actionable steps in eliminating the source of defects.
  3. The Kaizen philosophy emphasizes identifying inefficiencies in a process. The Five Whys helps teams uncover these inefficiencies and prioritize improvements accordingly.

Criticisms and Limitations of the Five Whys

Human Factor

The Five Whys technique relies heavily on people’s ability to accurately identify root causes, which can be influenced by personal bias or lack of expertise. This may lead to incorrect conclusions and can potentially hinder problem-solving efforts. Moreover, the technique does not account for complex issues with multiple root causes or unknown factors, which may require a more comprehensive approach.

For example, in a manufacturing setting, the reason for a machine malfunction might not be immediately apparent. A human operator might mistakenly attribute the issue to a single cause, such as inadequate maintenance, while ignoring other factors, such as equipment age or external influences like temperature fluctuations.

Overemphasis on Blame

The Five Whys approach can unintentionally create a focus on blaming individuals, teams, or departments for identified issues instead of fostering a culture of continuous improvement and shared responsibility. By repeatedly asking why, team members might feel that they are being interrogated and may become defensive, affecting morale and trust.

Other Problem-Solving Techniques

Fishbone Diagram

The Five Whys technique and the Fishbone Diagram both serve as problem-solving methodologies, but they have distinct differences. The Fishbone Diagram, also known as the cause-and-effect diagram, is a visual tool that illustrates the possible causes of a specific problem. It helps identify, sort and categorize these possible causes across several aspects, such as materials, equipment, process or people. It’s often used in engineering or manufacturing to pinpoint the root cause of defects.

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The Five Whys technique, on the other hand, relies on asking a series of “why” questions to delve into the reasons behind a problem. This method digs deeper into cause-and-effect relationships to uncover hidden issues or underlying factors that contribute to the problem.

  • Example 1: In a manufacturing process, there’s a high scrap rate. While Fishbone Diagram may identify multiple causes such as machine inaccuracy, employee skills, and poor materials, the Five Whys can dig deeper to find issues such as lack of problem-solving training.
  • Example 2: In an engineering project, delays keep happening. Fishbone Diagram may point to factors like resource constraints, human error, and communication breakdowns, while the Five Whys could uncover that the project manager isn’t taking proactive countermeasures to manage risks.

Learn more: Fishbone Diagram (Components, Factors, Examples)

Ishikawa Diagram

An Ishikawa Diagram is essentially another name for a Fishbone Diagram. It is so called because it was developed by Dr. Kaoru Ishikawa, who pioneered quality management processes in the Kawasaki shipyards. Just like the Fishbone Diagram, it serves as a visual representation of possible causes of a problem and categorizes them into various aspects, making it easier for the team to identify and address the root cause.

Compared to the Five Whys technique, the Ishikawa Diagram focuses on visually organizing causes, which can be particularly useful for complex problems with multiple factors. The Five Whys, while more straightforward, encourages a deeper understanding of the problem through a series of questions to uncover the root cause.

  • Example 1: A car manufacturing company faces frequent equipment breakdowns. An Ishikawa Diagram can categorize this issue under several factors like machinery, workforce, and maintenance, while the Five Whys could reveal that the company is not conducting regular inspections.
  • Example 2: A software company experiences a high rate of bugs in their projects. The Ishikawa Diagram might highlight issues related to design, coding, and testing, whereas the Five Whys can identify that the team is not using a proper defect tracking system.

Learn more: Ishikawa Diagram: Examples and Applications


Poka-Yoke is a Japanese term that translates to “mistake-proofing” or “error-proofing.” It’s a concept that focuses on preventing errors by designing processes and systems to eliminate human error or reduce its impact. Unlike the Five Whys technique, which aims to identify the root cause of a problem after it has happened, Poka-Yoke is a proactive approach to ensure that defects do not occur in the first place.

The Five Whys technique can complement Poka-Yoke by helping organizations understand how their processes have failed and subsequently implementing error-proofing measures based on the identified root causes.

  • Example 1: A packaging company has inconsistent sealing quality on their products. The Five Whys might reveal that the cause is the sealing machine’s varying temperatures, leading to the implementation of Poka-Yoke by installing an automatic temperature control system.
  • Example 2: A hospital faces cases of wrong medication being given to patients. Using the Five Whys may uncover that the issue is due to human error, leading to a Poka-Yoke solution, such as implementing barcode scanning to verify medication assignments.

Learn more: What is Poka-Yoke? (Examples, Principles, Methods)