Certified Six Sigma Black Belt Exam General 2 — Questions and Answers
Question 1: In the DMAIC cycle, which phase focuses on identifying root causes of defects using data analysis tools?
- Define
- Measure
- Analyze (Correct answer)
- Improve
Correct answer: Analyze
The Analyze phase uses statistical tools like fishbone diagrams and hypothesis testing to identify and verify root causes.
Question 2: Which Six Sigma metric represents the number of defects per million opportunities (DPMO) at a Six Sigma quality level?
- 3.4 (Correct answer)
- 6.0
- 233
- 66,807
Correct answer: 3.4
A true Six Sigma process produces no more than 3.4 DPMO, accounting for a 1.5 sigma long-term shift.
Question 3: A Black Belt is conducting a hypothesis test and sets alpha (α) = 0.05. What does this significance level represent?
- The probability of a Type II error
- The power of the test
- The acceptable probability of rejecting a true null hypothesis (Correct answer)
- The confidence interval width
Correct answer: The acceptable probability of rejecting a true null hypothesis
Alpha is the significance level representing the probability of committing a Type I error — rejecting a true null hypothesis.
Question 4: Which tool is most appropriate for prioritizing potential failure modes by their Risk Priority Number (RPN)?
- Control chart
- FMEA (Correct answer)
- SIPOC
- Affinity diagram
Correct answer: FMEA
Failure Mode and Effects Analysis (FMEA) calculates RPN by multiplying Severity, Occurrence, and Detection ratings to prioritize risks.
Question 5: What is the primary purpose of a Box-Cox transformation in Six Sigma analysis?
- To center the process mean at the target
- To normalize non-normal data before parametric testing (Correct answer)
- To convert attribute data to variable data
- To calculate process capability
Correct answer: To normalize non-normal data before parametric testing
The Box-Cox transformation applies a power function to non-normal data to make it approximately normal, enabling valid parametric analysis.
Question 6: In regression analysis, what does an R² value of 0.85 indicate?
- 85% of the variation in Y is explained by the model (Correct answer)
- The correlation coefficient is 0.85
- The model has 85% accuracy in predictions
- 15% of data points are outliers
Correct answer: 85% of the variation in Y is explained by the model
R² (coefficient of determination) indicates that 85% of the variability in the response variable is explained by the predictor variables in the model.
Question 7: Which phase of DMAIC is primarily responsible for establishing baseline process capability metrics?
- Define
- Measure (Correct answer)
- Analyze
- Control
Correct answer: Measure
The Measure phase collects data and calculates baseline metrics like Cp, Cpk, and sigma level to quantify current process performance.
Certified Six Sigma Black Belt Exam General 2
In the DMAIC cycle, which phase focuses on identifying root causes of defects using data analysis tools?