Lean Six Sigma Yellow Belt Certification Prep 3 — Questions and Answers
Question 1: A process produces 20 defects per 1,000 opportunities. What is the DPMO?
- 20,000 (Correct answer)
- 2,000
- 200
- 200,000
Correct answer: 20,000
DPMO = (defects / opportunities) × 1,000,000 = (20/1,000) × 1,000,000 = 20,000 DPMO.
Question 2: Which of the following best describes 'poka-yoke'?
- An error-proofing mechanism that prevents or detects defects (Correct answer)
- A type of control chart for attribute data
- A method for ranking process steps by value
- A Japanese term for continuous improvement
Correct answer: An error-proofing mechanism that prevents or detects defects
Poka-yoke refers to any mistake-proofing device or method designed to prevent errors or make defects immediately obvious.
Question 3: What is the purpose of a Measurement System Analysis (MSA)?
- To assess whether the measurement system introduces significant variation into the data (Correct answer)
- To identify the root cause of defects
- To prioritize improvement projects
- To calculate the process sigma level
Correct answer: To assess whether the measurement system introduces significant variation into the data
MSA (often a Gage R&R study) evaluates how much of the observed variation comes from the measurement system itself versus the actual process.
Question 4: In Lean thinking, 'overproduction' is considered waste because:
- It produces more than the customer currently needs, consuming resources and creating inventory (Correct answer)
- It increases cycle time for each individual unit
- It requires more skilled operators
- It reduces defect rates
Correct answer: It produces more than the customer currently needs, consuming resources and creating inventory
Overproduction is the worst Lean waste as it drives all other wastes — excess inventory, extra transportation, unnecessary motion, and storage costs.
Question 5: A Yellow Belt notices a process step takes 45 minutes but only 5 minutes of that adds value to the customer. What Lean metric captures this ratio?
- Process cycle efficiency (PCE) (Correct answer)
- Defects per unit (DPU)
- Overall equipment effectiveness (OEE)
- First pass yield (FPY)
Correct answer: Process cycle efficiency (PCE)
Process Cycle Efficiency = Value-Added Time / Total Lead Time; here PCE = 5/45 ≈ 11%, indicating significant waste.
Question 6: The 'voice of the customer' (VOC) is used in Six Sigma primarily to:
- Identify and prioritize customer needs that drive Critical to Quality (CTQ) characteristics (Correct answer)
- Measure internal process variation
- Train team members on quality tools
- Determine the project budget
Correct answer: Identify and prioritize customer needs that drive Critical to Quality (CTQ) characteristics
VOC captures customer requirements and expectations, which are then translated into measurable CTQ characteristics that guide the improvement project.
Question 7: Which type of data is counted rather than measured on a continuous scale?
- Attribute (discrete) data (Correct answer)
- Variable (continuous) data
- Ordinal data
- Interval data
Correct answer: Attribute (discrete) data
Attribute or discrete data represents counts or categories (e.g., number of defects, pass/fail), while variable data is measured on a continuous scale.
Lean Six Sigma Yellow Belt Certification Prep 3
A process produces 20 defects per 1,000 opportunities.
What is the DPMO?