Lean Six Sigma Yellow Belt Certification Root Cause Analysis 4 — Questions and Answers
Question 1: In the context of RCA, what does 'gemba' refer to?
- A Japanese term for the root cause of a defect
- Going to the actual place where the work is done to observe directly (Correct answer)
- A statistical tool for identifying variation
- A type of fishbone diagram used in service industries
Correct answer: Going to the actual place where the work is done to observe directly
'Gemba' means 'the real place' in Japanese and refers to going to where work actually happens to gather firsthand observations.
Question 2: A scatter diagram is used in root cause analysis primarily to:
- Display defect frequencies in ranked order
- Show the relationship or correlation between two variables (Correct answer)
- Map process steps and decision points
- Identify which defects occur most often
Correct answer: Show the relationship or correlation between two variables
A scatter diagram plots two variables to reveal whether a correlation exists, which can help confirm or rule out potential causes.
Question 3: Which of the following statements about the 5 Whys technique is TRUE?
- You must ask exactly 5 questions, no more and no less
- The technique always produces the same root cause regardless of who performs it
- The number 5 is a guideline; you stop when the root cause is reached (Correct answer)
- It is only effective for problems with a single cause
Correct answer: The number 5 is a guideline; you stop when the root cause is reached
The number 5 is a rule of thumb; the actual number of 'Why' questions asked depends on the complexity of the problem.
Question 4: A defect occurs only when a specific supplier's material is used. In a fishbone diagram, this most likely falls under which category?
- Man
- Machine
- Material (Correct answer)
- Method
Correct answer: Material
Supplier quality, raw materials, and components are classified under the 'Material' category in a fishbone diagram.
Question 5: When performing RCA, data stratification helps by:
- Calculating the cost of defects across the organization
- Breaking data into subgroups to identify patterns or hidden causes (Correct answer)
- Eliminating the need for a control chart
- Mapping the process from start to finish
Correct answer: Breaking data into subgroups to identify patterns or hidden causes
Stratification splits data by factors like shift, machine, or operator to reveal subgroup patterns that point to specific causes.
Question 6: What is the purpose of a 'corrective action' following root cause identification?
- To document the defect for future audits
- To permanently eliminate the root cause and prevent recurrence (Correct answer)
- To assign financial penalties to the responsible team
- To adjust the measurement system baseline
Correct answer: To permanently eliminate the root cause and prevent recurrence
A corrective action targets the root cause to permanently eliminate it and prevent the problem from happening again.
Question 7: During an RCA workshop, a facilitator asks the team to generate as many potential causes as possible without evaluation. This technique is called:
- Root cause validation
- Brainstorming (Correct answer)
- Fault tree analysis
- Kaizen event
Correct answer: Brainstorming
Brainstorming encourages open generation of ideas without judgment to ensure no potential cause is overlooked.
Lean Six Sigma Yellow Belt Certification Root Cause Analysis 4
In the context of RCA, what does 'gemba' refer to?