Certified Six Sigma Black Belt Exam Assessment 4 — Questions and Answers
Question 1: During a measurement system assessment, an appraiser consistently measures parts 0.5 mm higher than the true reference value across all ranges. This error is classified as:
- Repeatability
- Reproducibility
- Bias (Correct answer)
- Linearity
Correct answer: Bias
Bias is the systematic difference between the observed average measurement and the true (reference) value across all measurements.
Question 2: A process capability assessment yields Cp = 1.8 and Cpk = 0.9. What does this combination indicate?
- The process is centered and capable
- The process has adequate spread but is significantly off-center (Correct answer)
- The process is off-center with inadequate spread
- Both indices indicate a marginal process
Correct answer: The process has adequate spread but is significantly off-center
High Cp with low Cpk indicates the process has sufficient potential capability (spread fits within spec) but is poorly centered relative to specification limits.
Question 3: Which assessment approach quantifies the financial impact of poor quality, categorizing costs into prevention, appraisal, internal failure, and external failure?
- Balanced scorecard
- Cost of Poor Quality (COPQ) analysis (Correct answer)
- Throughput accounting
- Activity-based costing
Correct answer: Cost of Poor Quality (COPQ) analysis
COPQ analysis uses the PAF (Prevention, Appraisal, Failure) model to categorize and quantify quality-related costs.
Question 4: A linearity assessment of a measurement gauge shows that bias increases as the measured value increases. What corrective action is most appropriate?
- Retrain the appraisers
- Recalibrate the gauge across its full operating range (Correct answer)
- Replace all measurement gauges immediately
- Accept the gauge since all biases are below 5%
Correct answer: Recalibrate the gauge across its full operating range
Linearity error (bias varying with the magnitude of measurement) is corrected by calibrating the gauge across its entire operating range, not just at one point.
Question 5: During a process assessment, a Black Belt calculates a Z-score of 2.5 for the lower specification limit and 1.5 for the upper specification limit. What is Cpk?
- 2.0
- 0.83
- 0.50 (Correct answer)
- 1.25
Correct answer: 0.50
Cpk = min(Z_LSL, Z_USL) / 3 = min(2.5, 1.5) / 3 = 1.5 / 3 = 0.50.
Question 6: A Black Belt is assessing organizational readiness for a Six Sigma deployment. Which tool evaluates the maturity of processes against a defined capability framework?
- Benchmarking
- Process maturity assessment (e.g., CMMI) (Correct answer)
- Kaizen event
- Force field analysis
Correct answer: Process maturity assessment (e.g., CMMI)
Process maturity models like CMMI assess an organization's process capability across defined maturity levels, from initial to optimized.
Question 7: In a stability assessment, which pattern on a control chart indicates a process mean has shifted and the shift is statistically significant?
- One point beyond 3-sigma control limits
- Eight consecutive points on one side of the center line
- Two consecutive points beyond 2-sigma warning limits
- Both A and B are valid signals (Correct answer)
Correct answer: Both A and B are valid signals
Both a single point beyond 3-sigma limits and eight consecutive points on one side of the centerline are valid Western Electric rules indicating a statistically significant process shift.
Certified Six Sigma Black Belt Exam Assessment 4
During a measurement system assessment, an appraiser consistently measures parts 0.5 mm higher than the true reference value across all ranges.
This error is classified as: