Lean Six Sigma Yellow Belt Certification The Analyze Phase 2 — Questions and Answers
Question 1: Which tool is used to visually display the frequency distribution of a continuous variable during the Analyze phase?
- Control chart
- Histogram (Correct answer)
- SIPOC diagram
- Affinity diagram
Correct answer: Histogram
A histogram displays the frequency distribution of continuous data, helping identify patterns such as skewness or bimodality.
Question 2: A team discovers that 80% of defects come from 20% of the causes. Which principle does this represent?
- Central Limit Theorem
- Pareto Principle (Correct answer)
- Law of Large Numbers
- Normal Distribution Rule
Correct answer: Pareto Principle
The Pareto Principle (80/20 rule) states that roughly 80% of effects come from 20% of causes, helping teams prioritize root causes.
Question 3: What does a scatter diagram primarily help a team determine during the Analyze phase?
- The sequence of process steps
- The relationship between two variables (Correct answer)
- The frequency of defect types
- The capability of a process
Correct answer: The relationship between two variables
A scatter diagram plots two variables against each other to identify whether a correlation (positive, negative, or none) exists between them.
Question 4: In hypothesis testing, what does a p-value less than 0.05 typically indicate?
- Fail to reject the null hypothesis
- Reject the null hypothesis (Correct answer)
- The sample size is too small
- The data is not normally distributed
Correct answer: Reject the null hypothesis
A p-value below the significance level (commonly 0.05) indicates sufficient evidence to reject the null hypothesis.
Question 5: Which type of data analysis tool would best help identify whether a machine or operator is the dominant source of variation?
- Spaghetti diagram
- Stratification analysis (Correct answer)
- Value stream map
- Control plan
Correct answer: Stratification analysis
Stratification separates data by source (e.g., machine, shift, operator) to determine which factor contributes most to variation.
Question 6: A process has a Cp of 1.5 but a Cpk of 0.8. What does this indicate?
- The process spread is too wide for the specification
- The process is centered but has excessive variation
- The process has sufficient spread but is off-center (Correct answer)
- Both spread and centering are acceptable
Correct answer: The process has sufficient spread but is off-center
Cp measures potential capability (spread only) while Cpk accounts for centering; a high Cp with low Cpk means the process is capable but not centered on target.
Question 7: Which of the following best describes a 'vital few' in the context of the Analyze phase?
- All potential causes identified in a brainstorming session
- The small number of root causes responsible for most defects (Correct answer)
- The key process steps mapped in a SIPOC
- The team members assigned to the project
Correct answer: The small number of root causes responsible for most defects
The 'vital few' refers to the small set of root causes (from Pareto analysis) that drive the majority of quality problems.
