Lean Six Sigma Green Belt Certification Prep 3 — Questions and Answers
Question 1: A Green Belt team discovers that 80% of defects come from 20% of the causes. Which tool best visualizes this finding?
- Control chart
- Histogram
- Pareto chart (Correct answer)
- Box plot
Correct answer: Pareto chart
A Pareto chart visually displays the 80/20 rule by ranking causes from most to least frequent, helping teams prioritize improvement efforts.
Question 2: What is the sigma level of a process producing 3.4 defects per million opportunities (DPMO)?
- 3 sigma
- 4 sigma
- 5 sigma
- 6 sigma (Correct answer)
Correct answer: 6 sigma
Six Sigma quality is defined as 3.4 DPMO, which accounts for a 1.5 sigma long-term shift in the process mean.
Question 3: In a Design of Experiments (DOE), what is a 'main effect'?
- The overall average response across all runs
- The change in the response when a factor moves from its low to high level (Correct answer)
- The interaction between two factors
- The error term in the model
Correct answer: The change in the response when a factor moves from its low to high level
A main effect is the average change in the output response attributable to moving a single factor from its low level to its high level.
Question 4: Which measurement system analysis (MSA) metric measures the proportion of total process variation that is due to measurement error?
- Bias
- %Gauge R&R (Correct answer)
- Linearity
- Stability
Correct answer: %Gauge R&R
%Gauge R&R expresses measurement system variation as a percentage of total process variation, with values below 10% generally considered acceptable.
Question 5: What is 'Takt time' in Lean manufacturing?
- The time required to complete one cycle of a process
- The available production time divided by customer demand rate (Correct answer)
- The time a product spends waiting in queue
- The total time from order to delivery
Correct answer: The available production time divided by customer demand rate
Takt time is the rate at which products must be produced to match customer demand, calculated as available production time divided by demand volume.
Question 6: A Black Belt asks a Green Belt to perform a normality test on process data. Which test is most commonly used?
- F-test
- Anderson-Darling test (Correct answer)
- Mann-Whitney test
- Kruskal-Wallis test
Correct answer: Anderson-Darling test
The Anderson-Darling test is one of the most powerful and widely used tests for normality in Six Sigma projects, along with the Shapiro-Wilk test.
Question 7: In the context of Lean Six Sigma, what does 'VOC' stand for and why is it critical?
- Value of Change — quantifies project ROI
- Voice of the Customer — captures customer needs and expectations (Correct answer)
- Variance of Control — measures process stability
- Volume of Complaints — tracks defect frequency
Correct answer: Voice of the Customer — captures customer needs and expectations
Voice of the Customer (VOC) translates customer needs into measurable requirements (CTQs) that drive the entire Six Sigma improvement project.
Lean Six Sigma Green Belt Certification Prep 3
A Green Belt team discovers that 80% of defects come from 20% of the causes.
Which tool best visualizes this finding?