Certified Six Sigma Black Belt Exam Measurement System Analysis (MSA) 2 — Questions and Answers
Question 1: In a Gauge R&R study, what does the 'Reproducibility' component measure?
- Variation due to the gauge itself
- Variation when different operators measure the same part (Correct answer)
- Variation between different parts
- Variation due to environmental factors
Correct answer: Variation when different operators measure the same part
Reproducibility captures the variation introduced when different appraisers (operators) use the same gauge to measure the same parts.
Question 2: A %Tolerance method in MSA divides the total Gauge R&R variation by which value?
- Total process variation (6σ)
- The engineering tolerance (USL – LSL) (Correct answer)
- The part-to-part variation
- The study variation (5.15σ)
Correct answer: The engineering tolerance (USL – LSL)
The %Tolerance method evaluates whether gauge variation is acceptable relative to the specification width (USL minus LSL).
Question 3: Which index represents the ability of a measurement system to detect small shifts in the process mean?
- Cp
- Number of Distinct Categories (NDC) (Correct answer)
- Intraclass Correlation Coefficient
- %Contribution
Correct answer: Number of Distinct Categories (NDC)
The Number of Distinct Categories (NDC) indicates how many statistically distinct groups the measurement system can resolve in the process data.
Question 4: During an MSA study, an operator consistently reads a gauge 0.05 mm higher than the true value across all measurements. This is an example of:
- Linearity error
- Bias (Correct answer)
- Repeatability error
- Stability drift
Correct answer: Bias
Bias is a systematic, consistent offset between the observed average measurement and the true (reference) value.
Question 5: What is the primary purpose of using a control chart (X-bar and R chart) within a Gauge R&R study?
- To estimate process capability
- To detect operator-by-part interaction
- To verify that parts used in the study represent adequate variation (Correct answer)
- To calculate the %GRR directly
Correct answer: To verify that parts used in the study represent adequate variation
In a Gauge R&R study, control charts help confirm that selected parts span the actual process variation, which is necessary for a valid study.
Question 6: In the ANOVA method for Gauge R&R, which source of variation is uniquely captured compared to the Xbar-R method?
- Repeatability
- Reproducibility
- Operator-by-Part interaction (Correct answer)
- Gauge linearity
Correct answer: Operator-by-Part interaction
The ANOVA method separately quantifies the Operator × Part interaction, which the traditional Xbar-R method cannot isolate.
Question 7: A measurement system has a %GRR of 18% using the study variation method. How should this be classified according to AIAG guidelines?
- Acceptable — the system is adequate
- Marginal — may be acceptable depending on application (Correct answer)
- Unacceptable — the system must be improved before use
- Excellent — well below any threshold of concern
Correct answer: Marginal — may be acceptable depending on application
AIAG guidelines classify %GRR between 10% and 30% as marginal, requiring judgment based on the application's criticality.
Certified Six Sigma Black Belt Exam Measurement System Analysis (MSA) 2
In a Gauge R&R study, what does the 'Reproducibility' component measure?