CLL Quality Assurance & Improvement 3 — Questions and Answers
Question 1: In a control chart, a 'run of eight' consecutive points on one side of the centerline indicates:
- Normal random variation
- A potential special cause that should be investigated (Correct answer)
- The process is in statistical control
- The measurement system is miscalibrated
Correct answer: A potential special cause that should be investigated
A run of eight or more consecutive points on the same side of the centerline is a non-random pattern suggesting a special cause of variation.
Question 2: Which lean quality improvement approach focuses on reducing variation using statistical methods and follows a data-driven Define-Measure-Analyze-Improve-Control methodology?
- Total Quality Management (TQM)
- Six Sigma (Correct answer)
- ISO 9001
- Lean Manufacturing
Correct answer: Six Sigma
Six Sigma uses the DMAIC methodology and statistical tools to reduce process variation and defects to 3.4 per million opportunities.
Question 3: During a kaizen event focused on quality, the team discovers a step where operators frequently skip a check due to time pressure. The best lean response is to:
- Increase monitoring of that step
- Implement a poka-yoke that makes skipping the check impossible (Correct answer)
- Add more inspectors at that step
- Retrain operators on the importance of the check
Correct answer: Implement a poka-yoke that makes skipping the check impossible
Poka-yoke (mistake-proofing) physically or mechanically prevents errors from occurring, making it impossible to skip a critical quality step.
Question 4: What is the primary purpose of a Measurement System Analysis (MSA)?
- To validate that products meet customer specifications
- To assess whether the measurement system itself is capable of accurately detecting process variation (Correct answer)
- To determine sample sizes for inspection plans
- To calculate process capability indices
Correct answer: To assess whether the measurement system itself is capable of accurately detecting process variation
MSA evaluates the accuracy, repeatability, reproducibility, and stability of measurement systems to ensure the data being used for decisions is reliable.
Question 5: A process with a Cpk of 1.0 means:
- The process is centered and highly capable
- The process mean is at one of the specification limits (Correct answer)
- The process is perfectly centered between specification limits
- The process produces exactly 1% defects
Correct answer: The process mean is at one of the specification limits
A Cpk of 1.0 means the process mean is exactly three sigma away from the nearest specification limit, indicating the process is marginally capable but not centered.
Question 6: In lean quality, 'escaping defects' refers to:
- Defects that occur during rework operations
- Defects that pass through the process and reach the customer (Correct answer)
- Defects caught before the value stream begins
- Defects caused by supplier material issues
Correct answer: Defects that pass through the process and reach the customer
Escaping defects are quality failures that are not detected internally and ultimately reach the customer, representing the most costly type of quality failure.
Question 7: Which of the following is a key output of the Analyze phase in DMAIC?
- A validated improvement solution ready for pilot
- Identified and verified root causes of the problem (Correct answer)
- A control plan to sustain improvements
- A clearly defined problem statement and project scope
Correct answer: Identified and verified root causes of the problem
The Analyze phase uses data and statistical tools to identify and verify the root causes driving the problem defined in earlier phases.
CLL Quality Assurance & Improvement 3
In a control chart, a 'run of eight' consecutive points on one side of the centerline indicates: