Lean Six Sigma Green Belt Certification Prep 2 — Questions and Answers
Question 1: Which DMAIC phase focuses on identifying the root causes of a problem using statistical analysis?
- Define
- Measure
- Analyze (Correct answer)
- Improve
Correct answer: Analyze
The Analyze phase uses statistical tools and root cause analysis methods to identify the true sources of variation and defects.
Question 2: A process has a Cp of 1.5 but a Cpk of 0.8. What does this indicate?
- The process is centered and capable
- The process has sufficient spread but is off-center (Correct answer)
- The process is too narrow for the specification
- The process needs wider tolerances
Correct answer: The process has sufficient spread but is off-center
When Cp > Cpk, the process variation fits within spec limits but the mean is shifted away from the target, indicating a centering problem.
Question 3: What is the primary purpose of a SIPOC diagram in a Six Sigma project?
- To map detailed process steps with decision points
- To provide a high-level view of the process including Suppliers, Inputs, Process, Outputs, and Customers (Correct answer)
- To quantify defects per million opportunities
- To assign tasks to team members
Correct answer: To provide a high-level view of the process including Suppliers, Inputs, Process, Outputs, and Customers
A SIPOC diagram gives a high-level process overview that helps scope the project and identify key stakeholders before detailed mapping begins.
Question 4: In hypothesis testing, what does a p-value of 0.03 mean when the significance level (α) is 0.05?
- Fail to reject the null hypothesis
- Reject the null hypothesis (Correct answer)
- The test is inconclusive
- The sample size is too small
Correct answer: Reject the null hypothesis
Since p-value (0.03) < α (0.05), there is sufficient evidence to reject the null hypothesis.
Question 5: Which lean waste category describes producing more than customer demand requires?
- Waiting
- Overprocessing
- Overproduction (Correct answer)
- Inventory
Correct answer: Overproduction
Overproduction is considered the worst of the seven wastes in Lean because it generates other wastes like excess inventory and transportation.
Question 6: What statistical tool is used to test whether two or more population variances are equal?
- t-test
- ANOVA
- Levene's test (Correct answer)
- Chi-square test
Correct answer: Levene's test
Levene's test (and Bartlett's test) are used to assess the equality of variances across groups, an assumption required for many other statistical tests.
Question 7: During the Control phase, which tool is most appropriate for monitoring process stability over time?
- Pareto chart
- Control chart (Correct answer)
- Scatter diagram
- Fishbone diagram
Correct answer: Control chart
Control charts (SPC charts) are the primary tool used in the Control phase to monitor ongoing process performance and detect special cause variation.
Lean Six Sigma Green Belt Certification Prep 2
Which DMAIC phase focuses on identifying the root causes of a problem using statistical analysis?