Certified Six Sigma Black Belt Exam General 5 — Questions and Answers
Question 1: What is the primary goal of the Control phase in DMAIC?
- Identify additional improvement opportunities
- Sustain process gains and prevent reversion to old performance levels (Correct answer)
- Validate the measurement system accuracy
- Quantify the financial benefit of the project
Correct answer: Sustain process gains and prevent reversion to old performance levels
The Control phase implements control plans, updated SOPs, and monitoring systems to ensure the process improvements are maintained long-term.
Question 2: A Black Belt uses a scatter plot and finds r = −0.92 between two variables. What does this indicate?
- A weak positive linear relationship
- No meaningful relationship between the variables
- A strong negative linear relationship (Correct answer)
- A non-linear relationship between the variables
Correct answer: A strong negative linear relationship
A Pearson correlation coefficient of −0.92 indicates a strong negative linear relationship — as one variable increases, the other tends to decrease significantly.
Question 3: Which Lean waste category is represented when a machine operator waits for the previous step to complete before beginning their work?
- Defects
- Overproduction
- Waiting (Correct answer)
- Transportation
Correct answer: Waiting
Waiting is one of the eight Lean wastes (DOWNTIME), describing idle time when people, equipment, or materials are not moving or being worked on.
Question 4: A team is deciding between two process improvement solutions. Using a Pugh Concept Selection Matrix, what serves as the datum?
- The solution with the highest score
- The current process or a reference concept against which alternatives are compared (Correct answer)
- The solution recommended by the project sponsor
- The concept with the fewest negative ratings
Correct answer: The current process or a reference concept against which alternatives are compared
The datum in a Pugh Matrix is the baseline reference (often the current process) against which all alternative concepts are evaluated as better (+), worse (−), or same (S).
Question 5: In the context of Design for Six Sigma (DFSS), what does the DMADV roadmap stand for?
- Define, Measure, Analyze, Design, Verify (Correct answer)
- Define, Map, Analyze, Develop, Validate
- Design, Measure, Act, Define, Verify
- Develop, Measure, Analyze, Deploy, Verify
Correct answer: Define, Measure, Analyze, Design, Verify
DMADV stands for Define, Measure, Analyze, Design, Verify — a structured methodology used to design new products or processes to Six Sigma quality levels.
Question 6: What is the purpose of conducting a Normality test (e.g., Anderson-Darling) before performing a parametric statistical test?
- To determine if the sample size is adequate
- To verify that the data meets the normality assumption required by parametric tests (Correct answer)
- To identify outliers in the dataset
- To check if the variance is constant across groups
Correct answer: To verify that the data meets the normality assumption required by parametric tests
Parametric tests like t-tests and ANOVA assume the underlying population is normally distributed; the Anderson-Darling test checks whether this assumption is valid.
Question 7: A Black Belt discovers that the Cpk of a process is significantly lower than its Cp. What does this comparison reveal?
- The process has high variation relative to specifications
- The process is not centered — the mean is shifted toward one specification limit (Correct answer)
- The process is both off-center and highly variable
- The measurement system is inadequate
Correct answer: The process is not centered — the mean is shifted toward one specification limit
Cp measures potential capability (spread only), while Cpk accounts for both spread and centering; a large gap between them indicates the process mean is not centered within the specification limits.
Certified Six Sigma Black Belt Exam General 5
What is the primary goal of the Control phase in DMAIC?