Certified Six Sigma Black Belt Exam Measurement System Analysis 2 — Questions and Answers
Question 1: In a Gage R&R study, the %Contribution of Gage R&R to total variation is 18%. How is this generally interpreted?
- Acceptable — the gage accounts for less than 10% of variation
- Marginal — may be acceptable depending on application and customer requirements (Correct answer)
- Unacceptable — gage variation exceeds the product tolerance
- Excellent — any value below 25% is considered world-class
Correct answer: Marginal — may be acceptable depending on application and customer requirements
A %Contribution between 10–30% is generally considered marginal and may or may not be acceptable depending on the application.
Question 2: Which metric in a Gage R&R study directly quantifies the variation attributable to different operators measuring the same parts?
- Repeatability
- Reproducibility (Correct answer)
- Part-to-part variation
- Bias
Correct answer: Reproducibility
Reproducibility measures how much variation is introduced when different operators use the same gage to measure the same parts.
Question 3: A measurement system has a resolution of 0.1 mm and the process standard deviation is 0.08 mm. What is the primary concern?
- The gage is too precise for this application
- The gage resolution is too coarse to detect meaningful process variation (Correct answer)
- The gage will exhibit high reproducibility error
- Resolution is adequate because it equals the tolerance
Correct answer: The gage resolution is too coarse to detect meaningful process variation
When gage resolution is larger than the process variation, the measurement system cannot detect real changes in the process.
Question 4: In the context of MSA, what does 'discrimination ratio' (ndc) indicate?
- The ratio of gage bias to process variation
- The number of distinct categories the gage can reliably distinguish in the process (Correct answer)
- The ratio of repeatability to reproducibility
- The number of operators needed for a valid study
Correct answer: The number of distinct categories the gage can reliably distinguish in the process
The number of distinct categories (ndc) represents how many statistically distinct groups the measurement system can differentiate within the process variation.
Question 5: A stability study tracks the same reference part measured daily over 25 days. What statistical chart is most appropriate to monitor measurement system stability over time?
- Individuals and Moving Range (I-MR) chart (Correct answer)
- p-chart
- c-chart
- CUSUM chart
Correct answer: Individuals and Moving Range (I-MR) chart
An I-MR chart is used to monitor individual measurements of a reference standard over time to detect drift or shifts in measurement system stability.
Question 6: In an attribute Gage R&R (attribute agreement analysis), what does 'Kappa statistic' measure?
- The percentage of parts within specification
- The level of agreement between appraisers beyond what is expected by chance (Correct answer)
- The ratio of between-appraiser variation to within-appraiser variation
- The discrimination power of a go/no-go gage
Correct answer: The level of agreement between appraisers beyond what is expected by chance
Cohen's Kappa measures inter-rater agreement corrected for chance agreement, with values closer to 1.0 indicating stronger agreement.
Question 7: Which of the following would most likely cause high repeatability error in a Gage R&R study?
- Different operators using different measurement techniques
- Worn gage components or unstable fixturing (Correct answer)
- Parts being measured at different temperatures by different operators
- Inadequate training of one specific operator
Correct answer: Worn gage components or unstable fixturing
Repeatability (equipment variation) is affected by the gage itself — worn parts, loose fixtures, or instrument instability all increase within-appraiser variation.
Certified Six Sigma Black Belt Exam Measurement System Analysis 2
In a Gage R&R study, the %Contribution of Gage R&R to total variation is 18%.
How is this generally interpreted?