Lean Six Sigma Yellow Belt Certification Root Cause Analysis 3 — Questions and Answers
Question 1: Which of the following is a key limitation of the 5 Whys technique?
- It requires advanced statistical software
- It can lead different teams to different root causes for the same problem (Correct answer)
- It is only applicable to manufacturing processes
- It takes too long to complete for simple problems
Correct answer: It can lead different teams to different root causes for the same problem
The 5 Whys is subjective, so different teams may follow different causal chains and arrive at different root causes.
Question 2: In root cause analysis, a 'symptom' is best defined as:
- The measurable output of a process
- An observable sign that a problem exists, not the cause itself (Correct answer)
- The corrective action applied to a defect
- A category on a fishbone diagram
Correct answer: An observable sign that a problem exists, not the cause itself
A symptom is the visible evidence of a problem; effective RCA digs beneath symptoms to find the underlying cause.
Question 3: A Pareto chart shows that 80% of customer complaints come from 3 defect types. How does this support root cause analysis?
- It proves those 3 defects are caused by the same root cause
- It prioritizes which defects to investigate first for maximum impact (Correct answer)
- It eliminates the need for a fishbone diagram
- It identifies the corrective actions needed
Correct answer: It prioritizes which defects to investigate first for maximum impact
A Pareto chart applies the 80/20 rule to prioritize the most significant defects so RCA efforts target the highest-impact problems.
Question 4: Which action would you take FIRST when starting a root cause analysis?
- Implement a quick fix to stop the defect immediately
- Clearly define and scope the problem statement (Correct answer)
- Assign blame to the department responsible
- Build a fishbone diagram with all possible causes
Correct answer: Clearly define and scope the problem statement
A clear, well-scoped problem statement is essential before any analysis begins, ensuring the team investigates the right issue.
Question 5: The '6 M's' used in fishbone diagrams for manufacturing processes include Machine, Method, Material, Man, and Measurement. What is the sixth 'M'?
- Management
- Motivation
- Mother Nature (Environment) (Correct answer)
- Money
Correct answer: Mother Nature (Environment)
The sixth M is Mother Nature or Environment, which covers external environmental conditions that can affect a process.
Question 6: A team identifies that inadequate training is a root cause of process errors. This finding most directly belongs to which phase of DMAIC?
- Define
- Measure
- Analyze (Correct answer)
- Improve
Correct answer: Analyze
Root cause identification occurs in the Analyze phase of DMAIC, where data is studied to understand why problems occur.
Question 7: Which of the following scenarios would BEST validate that a root cause has been correctly identified?
- The project sponsor approves the root cause statement
- When the root cause is removed, the problem stops occurring (Correct answer)
- A majority of team members agree on the cause
- The cause appears on the fishbone diagram
Correct answer: When the root cause is removed, the problem stops occurring
True validation of a root cause is demonstrated when eliminating it results in the problem no longer occurring.
Lean Six Sigma Yellow Belt Certification Root Cause Analysis 3
Which of the following is a key limitation of the 5 Whys technique?