Certified Six Sigma Black Belt Exam Measurement System Analysis 5 â Questions and Answers
Question 1: What is the recommended minimum number of replicates per part-operator combination in a standard crossed Gage R&R study?
- 1
- 2 (Correct answer)
- 5
- 10
Correct answer: 2
AIAG MSA guidelines recommend at least 2 replicates per part-operator combination to estimate repeatability, with 3 replicates providing better estimates.
Question 2: A Black Belt is analyzing a Gage R&R study where repeatability variance = 0.04 and reproducibility variance = 0.01. What percentage of R&R is due to repeatability?
- 20%
- 25%
- 75%
- 80% (Correct answer)
Correct answer: 80%
Repeatability / (Repeatability + Reproducibility) = 0.04 / (0.04 + 0.01) = 0.04 / 0.05 = 80%.
Question 3: Which of the following MSA components assesses whether a gage reads differently when the same part is measured from high to low versus low to high values?
- Bias
- Hysteresis (Correct answer)
- Repeatability
- Stability
Correct answer: Hysteresis
Hysteresis is the difference in readings when a measurement is approached from opposite directions, common in mechanical and pressure-sensing instruments.
Question 4: In MSA, 'expanded uncertainty' as defined in ISO/IEC 17025 is expressed as the measurement result Âą U. The coverage factor k=2 corresponds approximately to which confidence level?
- 68%
- 90%
- 95% (Correct answer)
- 99%
Correct answer: 95%
A coverage factor of k=2 corresponds to approximately 95% confidence under a normal distribution, widely used in metrology laboratory reports.
Question 5: A process engineer wants to use a measurement system to set statistical process control (SPC) chart limits. Which MSA outcome most directly impacts the reliability of those control limits?
- Gage bias relative to the specification nominal
- Gage R&R %Study Variation relative to process variation (Correct answer)
- Gage linearity at the nominal value
- Gage calibration date
Correct answer: Gage R&R %Study Variation relative to process variation
Control chart limits are based on process variation; if gage variation is a large fraction of total variation, the control limits will be inflated and the chart will lose sensitivity to real process shifts.
Question 6: In a Gage R&R study, a master appraiser measures 10 parts 3 times each. The average range across all parts is 0.015. The d2* value for 3 replicates and 10 parts is 1.693. What is the estimated repeatability standard deviation?
- 0.00886 (Correct answer)
- 0.02540
- 0.01500
- 0.04500
Correct answer: 0.00886
Repeatability Ï = RĖ / d2* = 0.015 / 1.693 â 0.00886.
Question 7: Which of the following best explains why a measurement system can have low %R&R yet still be inadequate for the process?
- The process variation is so large that even a poor gage appears acceptable relative to it (Correct answer)
- Low %R&R always indicates a capable measurement system
- The gage has a large positive bias
- Repeatability is always the dominant source of error
Correct answer: The process variation is so large that even a poor gage appears acceptable relative to it
If process variation is very large (wide spread), even a mediocre gage will show a low %R&R because the denominator (process spread) is large â the gage may still be inadequate for detecting small shifts.
Certified Six Sigma Black Belt Exam Measurement System Analysis 5
What is the recommended minimum number of replicates per part-operator combination in a standard crossed Gage R&R study?