Lean Six Sigma Black Belt Certification Basic 3 — Questions and Answers
Question 1: Which statistical tool is most appropriate for determining whether a statistically significant difference exists between the means of three or more independent groups?
- Two-sample t-test
- One-way ANOVA (Correct answer)
- Chi-square test
- Paired t-test
Correct answer: One-way ANOVA
One-way ANOVA (Analysis of Variance) tests whether the means of three or more independent groups differ significantly by comparing within-group and between-group variance.
Question 2: In a control chart, what does a 'run of 8 consecutive points on one side of the center line' indicate?
- Random common cause variation
- A special cause that should be investigated (Correct answer)
- The process is in statistical control
- Normal measurement system error
Correct answer: A special cause that should be investigated
According to Western Electric rules, 8 or more consecutive points on the same side of the center line is a non-random pattern indicating a special cause of variation.
Question 3: Which document formally authorizes a Six Sigma project and assigns the Black Belt?
- Process map
- Project charter (Correct answer)
- Control plan
- Measurement system analysis report
Correct answer: Project charter
The project charter defines the project scope, goals, timeline, team roles, and business case, and it serves as the official authorization to proceed.
Question 4: The 7 wastes of Lean are represented by the acronym TIMWOOD. What does the 'M' stand for?
- Motion (Correct answer)
- Measurement
- Material
- Management
Correct answer: Motion
In TIMWOOD (Transportation, Inventory, Motion, Waiting, Over-processing, Overproduction, Defects), 'M' stands for Motion — unnecessary movement of people.
Question 5: A Gauge R&R study reveals that %GRR is 28%. How should this measurement system be classified?
- Acceptable — less than 30%
- Marginal — may be acceptable depending on context (Correct answer)
- Unacceptable — greater than 10%
- Excellent — less than 30%
Correct answer: Marginal — may be acceptable depending on context
A %GRR between 10% and 30% is considered marginal; acceptability depends on the application's importance and cost of measurement improvement.
Question 6: Which hypothesis is tested against the alternative hypothesis in inferential statistics?
- Research hypothesis
- Null hypothesis (Correct answer)
- Composite hypothesis
- Directional hypothesis
Correct answer: Null hypothesis
The null hypothesis (H₀) is the default assumption of no effect or no difference, which is tested and either rejected or failed to be rejected based on sample data.
Question 7: In a value stream map, which symbol typically represents a push arrow indicating inventory being pushed to the next step?
- A straight push arrow (Correct answer)
- A pull loop arrow
- A kaizen burst
- A data box
Correct answer: A straight push arrow
A straight push arrow in VSM indicates that material is pushed downstream regardless of actual need, as opposed to pull systems triggered by customer demand.
Lean Six Sigma Black Belt Certification Basic 3
Which statistical tool is most appropriate for determining whether a statistically significant difference exists between the means of three or more independent groups?