“5 Whys” technique for Root Cause Analysis (RCA)

Do you have a recurring problem that keeps on coming back despite repeated actions to address it? This might be an indication that you are treating the symptoms of the problem and not the actual problem itself – you need to determine the root cause of the problem – you must conduct a root cause analysis.

Root cause analysis (RCA) is a systematic process for identifying “root causes” of problems and the appropriate response that effectively deals with it. RCA is based on the basic idea that effective management requires more than merely “putting out fires” through quick fixes for problems that develop, but finding a way to prevent them from occurring again or in the first place. A root cause analysis is a process used to identify the primary source of a problem.

An effective method to get to the bottom of a problem is to use the “5 Whys” that was initially developed as part of TPS (Toyota Production System) that gave birth to what we know today as Lean Six Sigma – discussed in more detail in the article on “Lean Six Sigma – Organisational Development and Change”.

5 Whys is an iterative interrogative (problem solving) technique used to explore the cause-and-effect relationships underlying a particular problem.

The primary goal of the technique is to determine the root cause (source) of a defect or problem by repeating the question “Why?”, five times. Each answer forms the basis of the next question.

Why five time? This derives from an anecdotal observation on the number of iterations needed to resolve the problem.

How to conduct the 5 Why technique:

1. 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.
2. Ask Why the problem happens and write the answer down below the problem.
3. If the answer you just provided doesn’t identify the root cause of the problem that you wrote down in Step 1, ask Why again and write that answer down.
4. 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.

For example:

In business, only one cause for a problem is not the usual case. Using the 5 Whys in conjunction with the Fishbone Diagram (Ishikawa), that helps the exploration process to cover all potential inputs and hence potential causes of problems or defects.

 The 5 Whys method can be used to uncover multiple root causes by repeating the process asking a different sequence of questions each time.