CQE Inspection and Testing Methods 3 — Questions and Answers
Question 1: In a gage R&R study, 'repeatability' measures variation due to:
- Different operators using the same gage
- The same operator measuring the same part multiple times with the same gage (Correct answer)
- Part-to-part variation in the sample
- Environmental conditions during measurement
Correct answer: The same operator measuring the same part multiple times with the same gage
Repeatability (Equipment Variation) is the variation observed when one operator repeatedly measures the same part with the same gauge under identical conditions, reflecting the gauge's inherent measurement uncertainty.
Question 2: A process produces parts with a true mean of 50.1 mm against a target of 50.0 mm. The inspector's gauge consistently reads 50.3 mm. What type of measurement error is present?
- Repeatability error
- Linearity error
- Bias (accuracy error) (Correct answer)
- Stability error
Correct answer: Bias (accuracy error)
Bias is the systematic offset between the average measured value and the true (reference) value; here the gauge consistently reads 0.2 mm higher than the true part dimension.
Question 3: What is the purpose of a receiving inspection skip-lot program?
- To eliminate all receiving inspection costs
- To reduce inspection frequency for suppliers with proven quality history while maintaining quality protection (Correct answer)
- To skip inspection for rush orders only
- To transfer inspection responsibility entirely to the supplier
Correct answer: To reduce inspection frequency for suppliers with proven quality history while maintaining quality protection
Skip-lot programs reduce inspection frequency for suppliers demonstrating consistent quality, lowering inspection costs while maintaining quality protection through periodic sampling.
Question 4: In dimensional measurement, what does 'measurement uncertainty' represent?
- The probability of operator error
- The range within which the true value is expected to lie with a stated confidence level (Correct answer)
- The calibration due date tolerance
- The measurement equipment's age factor
Correct answer: The range within which the true value is expected to lie with a stated confidence level
Measurement uncertainty quantifies the doubt about a measurement result, expressing the range around the measured value within which the true value is expected to fall with a stated confidence level.
Question 5: Which inspection sampling approach is used when the cost of inspection is very high but the cost of passing a defective is also very high?
- Reduced inspection
- 100% inspection (complete inspection) (Correct answer)
- Skip-lot sampling
- Single sampling with a large AQL
Correct answer: 100% inspection (complete inspection)
When the consequences of defects reaching the customer are extremely high (safety-critical parts, high liability), 100% inspection is justified despite high cost to prevent any nonconforming units from escaping.
Question 6: What is the purpose of attribute agreement analysis (AAA) in measurement system analysis?
- To calibrate go/no-go gauges against standards
- To evaluate the consistency of operators making pass/fail decisions on the same parts (Correct answer)
- To determine the correct AQL for attribute inspection
- To calculate the sample size for attribute control charts
Correct answer: To evaluate the consistency of operators making pass/fail decisions on the same parts
Attribute Agreement Analysis assesses how consistently operators classify parts as conforming or nonconforming by having multiple operators evaluate the same parts multiple times and measuring agreement rates.
CQE Inspection and Testing Methods 3
In a gage R&R study, 'repeatability' measures variation due to: