Lean Six Sigma Green Belt Certification Analyze Phase Tools 4 — Questions and Answers
Question 1: A Green Belt performs a one-way ANOVA and obtains an F-statistic with p = 0.001. What is the correct interpretation?
- All group means are equal
- At least one group mean is significantly different from the others (Correct answer)
- All groups have different means from each other
- The variance within groups exceeds the variance between groups
Correct answer: At least one group mean is significantly different from the others
A significant ANOVA F-test indicates that at least one group mean differs, but does not specify which groups differ.
Question 2: What does a 'spaghetti diagram' reveal in the Analyze phase?
- The frequency distribution of defect types
- The physical flow path of people, materials, or products through a workspace (Correct answer)
- The statistical correlation between two continuous variables
- The hierarchical breakdown of potential failure modes
Correct answer: The physical flow path of people, materials, or products through a workspace
A spaghetti diagram traces actual movement paths in a physical layout to identify inefficient travel, backtracking, and waste.
Question 3: When using a cause-and-effect matrix, what are the rows and columns typically represent?
- Rows = defect types, Columns = process steps
- Rows = process inputs (Xs), Columns = key process outputs (Ys) (Correct answer)
- Rows = team members, Columns = action items
- Rows = control factors, Columns = noise factors
Correct answer: Rows = process inputs (Xs), Columns = key process outputs (Ys)
The C&E matrix rates each input (X) against each output (Y), helping prioritize which inputs most impact critical outputs.
Question 4: A Lean Six Sigma team finds that 20% of the product types account for 78% of customer complaints. Which tool was used to identify this insight?
- Scatter diagram
- Pareto chart (Correct answer)
- Control chart
- Box plot
Correct answer: Pareto chart
A Pareto chart ranks categories by frequency or impact, making it easy to identify the 'vital few' causes following the 80/20 principle.
Question 5: In a designed experiment, what is a 'confounded' effect?
- An effect that has been statistically confirmed as significant
- Two or more effects that cannot be separately estimated because they are aliased (Correct answer)
- An effect with a p-value greater than 0.05
- A factor that is held constant throughout the experiment
Correct answer: Two or more effects that cannot be separately estimated because they are aliased
Confounding (aliasing) occurs when two effects are mathematically indistinguishable from each other in a fractional factorial design.
Question 6: Which Analyze phase tool would a team use to determine whether process variation increased after a shift change by comparing the variance of two data sets?
- Two-sample t-test
- Chi-square goodness-of-fit test
- Levene's test or F-test for equal variances (Correct answer)
- Paired t-test
Correct answer: Levene's test or F-test for equal variances
Levene's test or the F-test (variance ratio test) directly compares the variances of two groups to determine if they are statistically different.
Question 7: A Green Belt uses a 'concentration diagram' during the Analyze phase. What information does this tool provide?
- The statistical distribution of defect counts over time
- The physical location of defects on a unit or product map (Correct answer)
- The correlation between two continuous variables
- The proportion of defects attributable to each cause category
Correct answer: The physical location of defects on a unit or product map
A concentration diagram overlays defect locations on a drawing or image of the unit to reveal spatial patterns in where defects occur.
Lean Six Sigma Green Belt Certification Analyze Phase Tools 4
A Green Belt performs a one-way ANOVA and obtains an F-statistic with p = 0.001.
What is the correct interpretation?