5 WHY Analysis is the key tool used to determine ROOT CAUSES for the Phenomenon identified in the
CHECK Phase of CAP-Do.
- The 5 Why analysis begins with the Summary of the Phenomenon from the 5W 1H analysis.
- The first “why?” originates from the Summary of the Phenomenon.
- The answer to the “why?” question (from the Summary of the Phenomenon) becomes the question of the second “why?”
- Follow this sequence until a root cause has been identified (through an answer to a “why?” question).
Note: If a root cause is identified before the 5th “why?” then the analysis is finished. It is unnecessary to complete all 5 whys if a root cause is identified early in the analysis.
![](https://leanmanufacturing.online/wp-content/uploads/2018/02/One-Point-Lesson-5-Why-Root-Cause-Analysis-OPL-1024x791.png)
![](https://leanmanufacturing.online/wp-content/uploads/2018/02/5-WHY-Analysis-Root-Cause-Identification-Breakdown-Preventative-Maintenance-791x1024.png)
Very powerful tool indeed and it helps you for analysis steps in no matter what is the project’s subject