Lean Six Sigma Yellow Belt Certification Root Cause Analysis 5 — Questions and Answers
Question 1: Which of the following is an example of a 'containment action' as opposed to a 'corrective action'?
- Retraining operators on the correct procedure
- Quarantining suspect inventory to prevent defective products from reaching customers (Correct answer)
- Updating the process FMEA with new failure modes
- Redesigning the production line layout
Correct answer: Quarantining suspect inventory to prevent defective products from reaching customers
A containment action is a short-term fix to stop defects from reaching customers while the root cause is being investigated.
Question 2: A team using a fishbone diagram places 'no standard operating procedure exists' under which category?
- Man
- Machine
- Measurement
- Method (Correct answer)
Correct answer: Method
Standard operating procedures (SOPs) govern how work is done, so their absence is a 'Method' category issue.
Question 3: Which of the following BEST differentiates root cause analysis from troubleshooting?
- Troubleshooting uses data; RCA uses only observation
- RCA seeks the systemic origin to prevent recurrence; troubleshooting restores function quickly (Correct answer)
- RCA is faster and less expensive than troubleshooting
- Troubleshooting always identifies the root cause
Correct answer: RCA seeks the systemic origin to prevent recurrence; troubleshooting restores function quickly
Troubleshooting focuses on restoring normal operation quickly, while RCA aims to permanently eliminate the underlying cause.
Question 4: A Lean Six Sigma team notices that defects spike whenever a new batch of reagent is introduced. The MOST appropriate next step in RCA is to:
- Add more inspectors at the end of the line
- Conduct a designed experiment comparing reagent batches to confirm the cause (Correct answer)
- Replace all reagent with the previous brand immediately
- Update the control plan without further investigation
Correct answer: Conduct a designed experiment comparing reagent batches to confirm the cause
Conducting a controlled experiment on reagent batches confirms whether the material is truly the cause before implementing a permanent fix.
Question 5: In root cause analysis, 'why-why analysis' and '5 Whys' are considered:
- Completely different techniques with no overlap
- The same iterative cause-finding approach (Correct answer)
- Statistical methods requiring software tools
- Only applicable to service industry problems
Correct answer: The same iterative cause-finding approach
'Why-why analysis' is simply another name for the 5 Whys — both describe iteratively asking why to drill down to the root cause.
Question 6: Which of the following scenarios represents treating a symptom rather than addressing the root cause?
- Updating the SOP after identifying an unclear instruction as the root cause
- Retesting all products after a calibration error caused out-of-spec results
- Repairing a machine repeatedly without investigating why it keeps breaking down (Correct answer)
- Retraining an operator after confirming lack of training caused the defect
Correct answer: Repairing a machine repeatedly without investigating why it keeps breaking down
Repeatedly repairing a machine without investigating the underlying cause means the root cause is never eliminated and the problem recurs.
Question 7: After completing root cause analysis and implementing corrective actions, which DMAIC phase ensures the improvements are sustained over time?
- Analyze
- Improve
- Control (Correct answer)
- Measure
Correct answer: Control
The Control phase uses control plans, monitoring, and updated SOPs to ensure that improvements from root cause analysis are maintained.
Lean Six Sigma Yellow Belt Certification Root Cause Analysis 5
Which of the following is an example of a 'containment action' as opposed to a 'corrective action'?