Farhan Hassan*
Analyzing by Five Whys


5-Whys is a part of the RCA [Root Cause Analysis] aspect that was developed by the Japanese inventor and industrialist Mr. Sakichi Toyoda for Toyota’s manufacturing processes in 1958. Also, used as a technique in the Analyze phase of the Six Sigma DMAIC (Define, Measure, Analyze, Improve, Control) methodology

It is a brainstorming tool by an iterative interrogative technique used to explore the cause-and-effect relationships underlying a particular problem to help the team identify the root cause(s) of a matter or a problem.



The concept here is by asking "Why?" five times successively, can you delve into a problem deeply enough to understand the ultimate root cause.

As by the fifth why the auditor should have identified or be close to identifying the root cause of the issue. 



• The answers come from people who have hands-on experience of the process or problem in question. 

• It can be used to complement the analysis necessary to complete a Cause & Effect diagram. 

• This methodology is can related to the Cause & Effect (Fishbone) diagram.


Example (Wikipedia):

The vehicle will not start. (The problem)

1. Why? : The battery is dead.

2. Why? : The alternator is not functioning.

3. Why? : The alternator belt has broken.

4. Why? : The alternator belt was well beyond its useful service life and not replaced. (Fourth why)

5. Why? : The vehicle was not maintained according to the recommended service schedule. (Fifth why, a root cause) 



The 5 Whys technique is an effective tool for root cause analysis in Lean management.

In workplace staffs face roadblocks in its daily work, the 5 Whys technique is simple also, effective tool for solving issues.

by finding the real reason for a given problem by asking a sequence of “Why” questions and eliminate these reasons ( answers) and to be sure that it will not be repeated in the future.

E-mail: fhshasn@gmail.com

Twitter: @farhan_939

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