CQE (CQE) 4 — Questions and Answers
Question 1: Which of the following best describes the purpose of a pre-control chart?
- Monitor process centering and spread using specification limits divided into zones (Correct answer)
- Replace the X-bar and R chart for large subgroup sizes
- Track attribute data when defect counts exceed 10 per unit
- Establish control limits from historical process data
Correct answer: Monitor process centering and spread using specification limits divided into zones
Pre-control divides the specification range into green, yellow, and red zones to provide simple run-rule decision making without calculating control limits.
Question 2: When performing a root cause analysis, a fishbone (Ishikawa) diagram organizes potential causes into categories such as:
- Plan, Do, Check, Act
- Manpower, Machines, Methods, Materials, Measurement, Environment (Correct answer)
- Prevention, Appraisal, Internal failure, External failure
- Define, Measure, Analyze, Improve, Control
Correct answer: Manpower, Machines, Methods, Materials, Measurement, Environment
The classic 6M fishbone categories are Manpower, Machines, Methods, Materials, Measurement, and Environment (Mother Nature).
Question 3: An organization implementing a corrective action system should ensure that corrective actions address:
- Symptoms of the nonconformance only
- The root cause to prevent recurrence (Correct answer)
- All future potential failures proactively
- Customer satisfaction scores exclusively
Correct answer: The root cause to prevent recurrence
Effective corrective action eliminates the root cause of a detected nonconformance to prevent it from recurring.
Question 4: The p-chart is the appropriate control chart for monitoring:
- Individual measurements from a continuous process
- The proportion of nonconforming items in variable-size subgroups (Correct answer)
- The count of defects per unit when subgroup size is constant
- Averages of subgroups when standard deviation is unknown
Correct answer: The proportion of nonconforming items in variable-size subgroups
The p-chart tracks fraction nonconforming (proportion) and accommodates variable subgroup sizes.
Question 5: Which statistical distribution is most appropriate for modeling time-to-failure data in reliability analysis?
- Normal distribution
- Binomial distribution
- Weibull distribution (Correct answer)
- Poisson distribution
Correct answer: Weibull distribution
The Weibull distribution is highly flexible and widely used in reliability analysis because its shape parameter β describes all three phases of the bathtub curve.
Question 6: Supplier qualification audits primarily assess whether a supplier:
- Offers the lowest unit cost among competing vendors
- Has a quality management system capable of meeting requirements (Correct answer)
- Employs statistical process control on all production lines
- Maintains ISO 9001 certification without exceptions
Correct answer: Has a quality management system capable of meeting requirements
Supplier qualification audits verify that a supplier's systems, processes, and capabilities can consistently meet the customer's quality requirements.
Question 7: In Design of Experiments (DOE), a confounded effect means that:
- Two or more effects cannot be estimated independently in the design (Correct answer)
- The experiment failed to achieve statistical significance
- A factor was set at the wrong level during the experiment
- Replication was insufficient to detect the main effects
Correct answer: Two or more effects cannot be estimated independently in the design
Confounding occurs when two or more effects are aliased — their estimates are mathematically combined and cannot be separated without additional runs.
CQE (CQE) 4
Which of the following best describes the purpose of a pre-control chart?