Lean Six Sigma Yellow Belt Certification Root Cause Analysis 2 — Questions and Answers
Question 1: In a fishbone diagram, which category would 'outdated software version' fall under?
- Machine (Correct answer)
- Method
- Material
- Measurement
Correct answer: Machine
Software or equipment issues are classified under the 'Machine' (or Equipment) category in a fishbone diagram.
Question 2: Which of the following best describes a 'contributing cause' in root cause analysis?
- The single event that directly caused the defect
- A factor that increased the likelihood of the root cause occurring (Correct answer)
- The documented corrective action taken
- The measurement system used to detect errors
Correct answer: A factor that increased the likelihood of the root cause occurring
A contributing cause is a factor that made the root cause more likely to occur but is not the root cause itself.
Question 3: A team uses the 5 Whys and reaches a conclusion that cannot be further questioned. This ending point is called the:
- Proximate cause
- Root cause (Correct answer)
- Symptom
- Effect
Correct answer: Root cause
The root cause is the deepest identifiable cause in a causal chain that, when corrected, prevents recurrence.
Question 4: Which tool is MOST effective for visually displaying the relationship between a problem and all its potential causes?
- Control chart
- Pareto chart
- Ishikawa diagram (Correct answer)
- Run chart
Correct answer: Ishikawa diagram
The Ishikawa (fishbone) diagram visually maps a problem to its potential causes across multiple categories.
Question 5: During root cause analysis, a team discovers the defect rate increases every Monday morning. What type of cause is this likely indicating?
- Random cause
- Special cause (Correct answer)
- Common cause
- Assignable cause variation within limits
Correct answer: Special cause
A recurring pattern tied to a specific condition (Monday mornings) is a special cause of variation, not random noise.
Question 6: A process produces defects mainly due to operator fatigue during the night shift. In a fishbone diagram, this belongs under which bone?
- Machine
- Method
- Man (People) (Correct answer)
- Mother Nature
Correct answer: Man (People)
Human factors such as fatigue, training, or behavior are categorized under the 'Man' or 'People' bone of the fishbone diagram.
Question 7: What is the primary purpose of verifying the root cause before implementing a solution?
- To document the timeline for auditors
- To ensure the fix addresses the actual source of the problem (Correct answer)
- To identify who is responsible for the defect
- To calculate the cost of poor quality
Correct answer: To ensure the fix addresses the actual source of the problem
Verifying the root cause ensures resources are not wasted on solutions that address symptoms rather than the true cause.
Lean Six Sigma Yellow Belt Certification Root Cause Analysis 2
In a fishbone diagram, which category would 'outdated software version' fall under?