ISA CAP Quality Assurance & Improvement 2 — Questions and Answers
Question 1: Which statistical tool is used to separate the 'vital few' causes from the 'trivial many' in a quality improvement effort?
- Histogram
- Pareto chart (Correct answer)
- Control chart
- Scatter diagram
Correct answer: Pareto chart
A Pareto chart ranks causes by frequency or impact, highlighting the vital few causes responsible for most defects.
Question 2: What does Cp measure in process capability analysis?
- Process centering relative to specification limits
- Potential capability assuming the process is centered (Correct answer)
- The number of defects per million opportunities
- Variation due to special causes
Correct answer: Potential capability assuming the process is centered
Cp measures potential process capability by comparing the specification width to the process spread, assuming the process is centered.
Question 3: A control chart shows a run of 8 consecutive points on one side of the centerline. This pattern indicates:
- Random common cause variation
- A non-random signal suggesting a process shift (Correct answer)
- Measurement system error
- Overcontrol of the process
Correct answer: A non-random signal suggesting a process shift
Eight or more consecutive points on one side of the centerline is a Western Electric run rule violation indicating a likely process shift.
Question 4: Which quality improvement methodology follows the DMAIC cycle?
- Total Quality Management (TQM)
- Six Sigma (Correct answer)
- ISO 9001
- Lean Manufacturing
Correct answer: Six Sigma
Six Sigma uses the DMAIC (Define, Measure, Analyze, Improve, Control) cycle as its core problem-solving framework.
Question 5: In a measurement system analysis (MSA), 'reproducibility' refers to:
- Variation when one operator measures the same part repeatedly
- Variation between different operators measuring the same part (Correct answer)
- The ability of the gauge to detect small differences
- Consistency of the measurement over time
Correct answer: Variation between different operators measuring the same part
Reproducibility captures the variation in measurements taken by different operators using the same gauge on the same parts.
Question 6: What is the primary purpose of an FMEA (Failure Mode and Effects Analysis) in quality assurance?
- Document corrective actions after failures occur
- Proactively identify and prioritize potential failure modes before they occur (Correct answer)
- Measure process capability against specifications
- Track defect rates over time using control charts
Correct answer: Proactively identify and prioritize potential failure modes before they occur
FMEA is a proactive risk assessment tool used to identify potential failure modes, their effects, and to prioritize preventive actions.
Question 7: When a process has a Cpk value of 1.33, this generally means the process:
- Is barely meeting specifications and needs immediate improvement
- Is capable with acceptable margin within specifications (Correct answer)
- Has excessive variation relative to specifications
- Is perfectly centered with zero defect rate
Correct answer: Is capable with acceptable margin within specifications
A Cpk of 1.33 corresponds to roughly 4-sigma performance, indicating the process is capable and producing within specifications with acceptable margin.
ISA CAP Quality Assurance & Improvement 2
Which statistical tool is used to separate the 'vital few' causes from the 'trivial many' in a quality improvement effort?