C2 Quality Assurance and Improvement 3 — Questions and Answers
Question 1: Which quality cost category includes rework, scrap, and re-inspection performed before product delivery?
- External failure costs
- Appraisal costs
- Internal failure costs (Correct answer)
- Prevention costs
Correct answer: Internal failure costs
Internal failure costs arise from defects discovered and corrected before the product reaches the customer.
Question 2: A fishbone (Ishikawa) diagram categorizes potential causes under which classic set of headings in manufacturing?
- Plan, Do, Check, Act
- Man, Machine, Material, Method, Measurement, Environment (Correct answer)
- Define, Measure, Analyze, Improve, Control
- Inputs, Process, Outputs, Feedback, Controls
Correct answer: Man, Machine, Material, Method, Measurement, Environment
The 6M categories (Man, Machine, Material, Method, Measurement, Environment) structure cause-and-effect analysis in manufacturing.
Question 3: Process capability index Cpk differs from Cp in that Cpk:
- Uses the overall standard deviation instead of the within-subgroup standard deviation
- Accounts for how well the process mean is centered between specification limits (Correct answer)
- Is only applicable to attribute data
- Requires a minimum sample size of 500
Correct answer: Accounts for how well the process mean is centered between specification limits
Cpk adjusts for process centering by taking the minimum of the upper and lower capability ratios.
Question 4: In the DMAIC improvement cycle, which phase is specifically focused on identifying and validating the root causes of the problem?
- Define
- Measure
- Analyze (Correct answer)
- Improve
Correct answer: Analyze
The Analyze phase uses data and tools like hypothesis testing and fishbone diagrams to confirm root causes.
Question 5: An organization receives a customer complaint about product quality after delivery. The corrective action cost to resolve this complaint is classified as:
- Prevention cost
- Appraisal cost
- Internal failure cost
- External failure cost (Correct answer)
Correct answer: External failure cost
External failure costs are incurred when defects reach customers, including warranty, returns, and complaint handling.
Question 6: Which sampling method divides a population into subgroups and then randomly samples from each subgroup?
- Simple random sampling
- Systematic sampling
- Stratified sampling (Correct answer)
- Cluster sampling
Correct answer: Stratified sampling
Stratified sampling ensures representation from each subgroup by sampling proportionally or equally from each stratum.
Question 7: A SIPOC diagram is used during which phase of DMAIC?
- Analyze
- Improve
- Control
- Define (Correct answer)
Correct answer: Define
SIPOC (Suppliers, Inputs, Process, Outputs, Customers) is a high-level process map created in the Define phase to scope the project.
C2 Quality Assurance and Improvement 3
Which quality cost category includes rework, scrap, and re-inspection performed before product delivery?