5Y analysis

1. L3 CPS 5 WHY ROOT CAUSE ANALYSIS WORKSHEET:
 When performing root cause analysis, always address why the nonconforming product was produced and why it was passed on to the
internal or external customer, “why made and why shipped”.
 Keep in mind the following key phrase as a background thought in this 5 why exercise: "People do not fail, processes do!"
Why did the problem occur?
1. Why is
that?
2. Why is
that?
3. Why is
that?
4. Why is
that?
 Root Cause-the lowest level of cause
that can be counter measured:
5.

2. L3 CPS 5 WHY ROOT CAUSE ANALYSIS WORKSHEET:
Example:
 Problem Statement - My car will not start.
1. The battery is dead. Why is
that?
2. The alternator is not functioning. Why is
that?
3. The alternator belt has broken. Why is
that?
4. The alternator belt was well beyond its useful service life
and has never been replaced.
Why is
that?
Note that in this example the fifth
why suggests a broken process or a
behavior that can be altered and
measured.
5. I have not been maintaining my car according to the recommended service schedule.

3. L3 CPS 5 WHY ROOT CAUSE ANALYSIS WORKSHEET:
Root Cause analysis guidelines:
1. Identify and Verify Root Cause(s). Identify all potential causes which could explain why the problem occurred. Isolate and verify the root
cause(s) by testing potential causes against the problem description and test data.
2. Brainstorming sessions should be used to identify potential causes. Brainstorming rules are as follows:
 Focus on the problem by repeating the problem statement often.
 Listen carefully for “evaluative comments” and stop them immediately.
 Reward all team members for their inputs.
 Clarify potential causes if they are unclear but don’t do the clarifying for someone.
 If someone is having difficulty, review ideas already mentioned.
 If they are still having difficulty, move on to avoid frustrating them.
Note: When brainstorming, quantity of ideas is more important than quality of ideas.
3. Identify and remove unlikely potential causes using common sense and team consensus/voting.
4. Review all potential causes to determine if any are underlying causes to other possible causes on the list.
5. Investigate each remaining potential cause. Coordinate parallel activities with different members to help expedite the process of
verification.
6. Classify the remaining potential causes using the 5M’s.
 Man
 Method
 Material
 Machine
 Measurement
7. The following tools can be used to help Identify the root cause.
 Fishbone Diagrams
 Mind Mapping
 Note: When performing root cause analysis, ask why, why, why as necessary to identify the lowest level cause that can be counter
measured, (the root cause).When performing the root cause analysis, address why the nonconforming product was produced and why
it was passed on to the customer, (internal or external).
8. Verify the root cause(s) by conducting with/without studies. Can you generate the problem?