Lean Six Sigma Black Belt Certification Define and Measure Phases 4 — Questions and Answers
Question 1: During the Measure phase, a team discovers that operators were trained differently, causing measurement bias. Which MSA study specifically assesses whether a gauge produces different readings at different parts of its measurement range?
- Repeatability study
- Linearity study (Correct answer)
- Stability study
- Attribute agreement analysis
Correct answer: Linearity study
Linearity analysis evaluates whether the gauge's bias is consistent across its operating range by comparing bias at low, mid, and high reference values.
Question 2: In a DMAIC project charter, the 'business case' section primarily answers which question?
- What is the root cause of the problem?
- Why is solving this problem important to the organization? (Correct answer)
- How will the solution be implemented?
- Who are the process owners?
Correct answer: Why is solving this problem important to the organization?
The business case articulates the strategic and financial importance of the project to justify resource allocation and leadership support.
Question 3: A team creates a detailed process map and identifies a step where product sits idle for 3 hours. Using Lean terminology, what type of waste is this?
- Overprocessing
- Defects
- Waiting (Correct answer)
- Overproduction
Correct answer: Waiting
Idle time between process steps is classified as 'Waiting' waste (one of the 8 wastes in Lean), which adds no value to the product.
Question 4: Which sampling method divides the population into subgroups and randomly selects samples from each subgroup proportionally?
- Simple random sampling
- Systematic sampling
- Stratified random sampling (Correct answer)
- Convenience sampling
Correct answer: Stratified random sampling
Stratified random sampling ensures representation from all relevant subgroups (strata), reducing sampling error and improving estimate precision.
Question 5: A process mean is exactly centered between the upper and lower specification limits. If the process standard deviation is σ, and the spec width is 12σ, what is the Cpk?
- 1.0
- 1.5
- 2.0 (Correct answer)
- 3.0
Correct answer: 2.0
When centered, Cpk = Cp = (USL − LSL) / (6σ) = 12σ / 6σ = 2.0, indicating an extremely capable process.
Question 6: A team collects baseline data and finds the process is not normally distributed. Which capability index is most appropriate when the distribution is skewed?
- Cp
- Cpk
- Pp
- Ppk using non-normal transformation or percentile method (Correct answer)
Correct answer: Ppk using non-normal transformation or percentile method
When data is non-normal, Ppk calculated after a Box-Cox transformation or using the percentile method provides a valid capability estimate.
Question 7: In the Define phase, a team's problem statement should NOT include which of the following?
- Quantified magnitude of the problem
- Timeframe of the problem
- Proposed root cause or solution (Correct answer)
- Business impact of the problem
Correct answer: Proposed root cause or solution
A good problem statement describes WHAT is wrong without presupposing WHY or HOW to fix it — solutions belong in later DMAIC phases.
Lean Six Sigma Black Belt Certification Define and Measure Phases 4
During the Measure phase, a team discovers that operators were trained differently, causing measurement bias.
Which MSA study specifically assesses whether a gauge produces different readings at different parts of its measurement range?