five why technique

“5 Whys” Technique – An Investigation Tool

The Five Whys Technique is a simple problem-solving technique that helps to get to the root of a problem quickly only by asking “Why?” five times successively.


  • The 5-Whys is a simple brainstorming tool that can help QI teams to identify the root cause(s) of a problem. Once a general problem has been recognized (either using the Fishbone Diagram or Process Mapping), ask “why” questions to drill down to the root causes.
  • Asking the 5-Whys allows teams to move beyond obvious answers and reflect on less obvious explanations or causes.
  • “5 whys” method requires the investigator to start with a precise and focused problem statement, then take the problem statement and ask “why” several times to get to the root of the problem.
  • It is said that only by asking “Why?” five times successively, can you delve into a problem deeply enough to understand the ultimate root cause. By the time you get to the 4th or 5th why, you will likely be looking squarely at management practices (more than five whys may be required for complex problems).
  • This methodology is closely related to the Cause & Effect (Fishbone) diagram, and can be used to complement the analysis necessary to complete a Cause & Effect diagram.


  • Root cause analysis is a structured team process that assists in identifying underlying factors or causes of an event, such as an adverse event or near –miss.
  • Understanding the contributing factors or causes of a system failure can help to develop actions that sustain corrections.
  • The Five Whys Technique is a simple problem-solving technique that helps to get to the root of a problem quickly.
  • The Five Whys strategy involves looking at any problem and drilling down by asking: “Why?” or “What caused this problem?”
  • While you want clear and concise answers, you want to avoid answers that are too simple and overlook important details.
  • Typically, the answer to the first “why” should prompt another “why” and the answer to the second “why” will prompt another and so on; hence the name Five Whys.
  • This technique can help you to quickly determine the root cause of a problem.
  • It’s simple, and easy to learn and apply.


  • The team conducting this root cause analysis does the following:
  • Develops the problem statement.  Be clear and specific.
  • The team facilitator asks why the problem happened and records the team response. To determine if the response is the root cause of the problem, the facilitator asks the team to consider “If the most recent response were corrected, is it likely the problem would reoccur?” If the answer is yes, it is likely this is a contributing factor, not a root cause.
  • If the answer provided is a contributing factor to the problem, the team keeps asking “Why?” until there is agreement from the team that the root cause has been identified.
  • It often takes three to five whys, but it can take more than five! So keep going until the team agrees the root cause has been identified.


  • Include people with personal knowledge of the processes and systems involved in the problem being discussed.
  • Note that the Five Whys technique may not always help you to identify the root cause. Another technique you might consider is the fishbone diagram. The fishbone diagram forces you to think broadly across various categories that could be causing or contributing to the problem
  • Interestingly, the“5 whys” approach may be combined with another tool Brainstorming in such a way that results in out-of-the-box thinking.
  • It also helps prevent anyone from jumping to easy conclusions.
  • Indeed, it creates an atmosphere that forces hard questioning.
  • Furthermore, it keeps the process moving until it starts uncovering objective evidence that will hold upto the scrutiny of regulatory authorities.

Benefits of the “5 Whys”

  • Helps to identify the root cause of a problem.
  • Determine the relationship between different root causes of a problem.
  • One of the simplest tools; easy to complete without statistical analysis.

When Is “5 Whys” Most Useful?

  • When problems involve human factors or interactions.
  • In day-to-day business life; can be used within or without a Six Sigma project.

How to Complete the “5 Whys “?

  • Write down the specific problem. Writing the issue helps you formalize the problem and describe it completely. It also helps a team focus on the same problem.
  • Ask Why the problem happens and write the answer down below the problem.
  • If the answer you just provided does not identify the root cause of the problem that you wrote down in Step 1, ask Why again and write that answer down.
  • Loop back to step 3 until the team is in agreement that the problem’s root cause is identified. Again, this may take fewer or more times than five Whys.


5 Whys Examples
  • Problem Statement: Customers are unhappy because they are being shipped products that do not meet their specifications.
  1. Why are customers being shipped bad products?

Because manufacturing built the products to a specification that is different from what the customer and the sales person agreed to.

2. Why did manufacturing build the products to a different specification than that of sales?

Because the sales person expedites work on the shop floor by calling the head of manufacturing directly to begin work. An error happened when the specifications were being communicated or written down.

3. Why does the sales person call the head of manufacturing directly to start work instead of following the procedure established in the company?

Because the “start work” form requires the sales director’s approval before work can begin and slows the manufacturing process (or stops it when the director is out of the 

4. Why does the form contain an approval for the sales director?

Because the sales director needs to be continually updated on sales for discussions with the CEO.

  • In this case, only four Whys were required to find out that a non-value added signature authority is helping to cause a process breakdown.

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