Lean Six Sigma Yellow Belt Certification The Analyze Phase 3 — Questions and Answers
Question 1: What is the primary purpose of a Fishbone (Ishikawa) diagram in the Analyze phase?
- To map the flow of materials through a facility
- To organize and display potential causes of a problem (Correct answer)
- To track defect counts over time
- To calculate process sigma level
Correct answer: To organize and display potential causes of a problem
A Fishbone diagram visually organizes potential causes of a problem into categories (e.g., Man, Machine, Method, Material) to facilitate root cause analysis.
Question 2: During root cause analysis, a team repeatedly asks 'why' after each answer. After five iterations they identify an equipment calibration issue. What technique did they use?
- FMEA
- 5 Whys (Correct answer)
- Regression analysis
- Benchmarking
Correct answer: 5 Whys
The 5 Whys technique iteratively asks 'why' to drill past symptoms and surface the true root cause of a problem.
Question 3: Which statement about correlation and causation is correct in Lean Six Sigma analysis?
- A strong correlation always proves causation
- Correlation indicates a relationship but does not prove causation (Correct answer)
- Causation can only be established through scatter diagrams
- Negative correlation implies no relationship exists
Correct answer: Correlation indicates a relationship but does not prove causation
Correlation shows that two variables move together, but additional analysis (such as DOE or subject matter expertise) is required to establish a causal relationship.
Question 4: A Yellow Belt team is analyzing cycle time data and finds a data point far outside the typical range. What is this called?
- A stratified sample
- A mode
- An outlier (Correct answer)
- A confidence interval
Correct answer: An outlier
An outlier is a data point that falls significantly outside the expected range and can distort analysis if not investigated and addressed appropriately.
Question 5: In a Lean Six Sigma Analyze phase, what does 'value-added' activity mean?
- Any activity that uses resources
- An activity the customer is willing to pay for that transforms the product (Correct answer)
- An activity required by internal policy
- An activity that reduces defects
Correct answer: An activity the customer is willing to pay for that transforms the product
A value-added activity must meet three criteria: the customer is willing to pay for it, it transforms the product or service, and it is done correctly the first time.
Question 6: Which graphical tool shows individual data points over time and includes control limits to detect special cause variation?
- Pareto chart
- Box plot
- Control chart (Correct answer)
- Histogram
Correct answer: Control chart
A control chart (run chart with control limits) distinguishes between common cause (random) variation and special cause (assignable) variation over time.
Question 7: A team wants to determine if there is a statistically significant difference between the defect rates of two shifts. Which tool is most appropriate?
- Spaghetti diagram
- Hypothesis test (e.g., 2-proportion test) (Correct answer)
- SIPOC diagram
- Affinity diagram
Correct answer: Hypothesis test (e.g., 2-proportion test)
A 2-proportion hypothesis test statistically compares defect rates between two groups to determine if the difference is real or due to chance.
Lean Six Sigma Yellow Belt Certification The Analyze Phase 3
What is the primary purpose of a Fishbone (Ishikawa) diagram in the Analyze phase?