CMS Quality Control & Assurance 2 — Questions and Answers
Question 1: Which statistical tool is used to separate the vital few causes of defects from the trivial many?
- Histogram
- Pareto chart (Correct answer)
- Scatter diagram
- Run chart
Correct answer: Pareto chart
A Pareto chart applies the 80/20 rule to rank defect causes so teams focus on the vital few that drive most problems.
Question 2: A process capability index (Cpk) of 1.33 indicates that the process is:
- Incapable and requires immediate improvement
- Marginally capable at minimum industry standard
- Capable with a 4-sigma margin from the nearest specification limit (Correct answer)
- Operating at Six Sigma performance level
Correct answer: Capable with a 4-sigma margin from the nearest specification limit
Cpk = 1.33 corresponds to a 4-sigma separation from the nearest spec limit, which is the traditional minimum acceptable capability.
Question 3: What does a C-chart monitor in statistical process control?
- The number of defects per unit when sample size varies
- The proportion of defective items in a sample
- The count of defects on a single unit of fixed size (Correct answer)
- The average measurement within a subgroup
Correct answer: The count of defects on a single unit of fixed size
A C-chart tracks the number of defects (nonconformities) per inspection unit when the sample size is constant.
Question 4: During a measurement system analysis (MSA), 'reproducibility' refers to:
- Variation caused by the measurement instrument itself
- Variation when different operators measure the same part (Correct answer)
- The ability to repeat measurements within a short time
- Bias between the gauge reading and a reference standard
Correct answer: Variation when different operators measure the same part
Reproducibility is the variation in measurements taken by different appraisers using the same gauge on the same parts.
Question 5: Which quality cost category includes scrap, rework, and warranty repairs?
- Prevention costs
- Appraisal costs
- Internal and external failure costs (Correct answer)
- Conformance costs
Correct answer: Internal and external failure costs
Scrap and rework are internal failure costs; warranty repairs are external failure costs — both fall under the failure cost category.
Question 6: An OC (Operating Characteristic) curve for an acceptance sampling plan shows the relationship between:
- Process spread and specification limits
- Incoming lot quality and probability of acceptance (Correct answer)
- Sample size and inspection time
- Defect rate and control chart limits
Correct answer: Incoming lot quality and probability of acceptance
The OC curve plots lot percent defective (X-axis) against the probability that the sampling plan will accept that lot (Y-axis).
Question 7: In FMEA, the Risk Priority Number (RPN) is calculated as:
- Severity × Occurrence
- Severity + Occurrence + Detection
- Severity × Occurrence × Detection (Correct answer)
- Occurrence × Detection / Severity
Correct answer: Severity × Occurrence × Detection
RPN = Severity × Occurrence × Detection, and higher RPN values flag failure modes requiring priority corrective action.
CMS Quality Control & Assurance 2
Which statistical tool is used to separate the vital few causes of defects from the trivial many?