Lean Six Sigma Black Belt Certification Basic 5 — Questions and Answers
Question 1: Which analysis technique identifies the vital few causes responsible for the majority of defects, based on the 80/20 rule?
- Fishbone diagram
- Pareto analysis (Correct answer)
- Box plot
- Histogram
Correct answer: Pareto analysis
Pareto analysis applies the 80/20 principle to prioritize the vital few causes (roughly 20%) that account for the majority (roughly 80%) of defects or problems.
Question 2: In a full factorial DOE with 3 factors each at 2 levels, how many experimental runs are required (without replication)?
- 6
- 8 (Correct answer)
- 9
- 12
Correct answer: 8
A 2³ full factorial design requires 2³ = 8 experimental runs to test all combinations of 3 factors at 2 levels each.
Question 3: Which Lean concept refers to the rate at which a system must produce to meet customer demand?
- Cycle time
- Takt time (Correct answer)
- Lead time
- Throughput time
Correct answer: Takt time
Takt time = Available production time ÷ Customer demand rate, and it sets the production rhythm needed to satisfy customer demand without over- or under-producing.
Question 4: A Black Belt wants to test if the variance of two independent processes is statistically different. Which test should be used?
- Two-sample t-test
- F-test (Levene's or Bartlett's test) (Correct answer)
- Mann-Whitney U test
- Kruskal-Wallis test
Correct answer: F-test (Levene's or Bartlett's test)
The F-test, Levene's test, or Bartlett's test compares the variances of two or more groups to determine if they are statistically different.
Question 5: Which Six Sigma role is typically responsible for removing organizational roadblocks and ensuring resource availability for Black Belt projects?
- Master Black Belt
- Champion/Sponsor (Correct answer)
- Green Belt
- Process Owner
Correct answer: Champion/Sponsor
Champions or Sponsors are senior leaders who own the business results of Six Sigma projects, remove obstacles, secure resources, and align projects with strategic goals.
Question 6: Process capability index Cpk differs from Cp in that Cpk:
- Uses the overall standard deviation instead of the within-subgroup standard deviation
- Accounts for process centering relative to specification limits (Correct answer)
- Measures long-term capability only
- Is calculated without upper or lower specification limits
Correct answer: Accounts for process centering relative to specification limits
Cpk accounts for both spread and centering by using the minimum of (USL−mean)/3σ and (mean−LSL)/3σ, so a shifted process will have a lower Cpk than Cp.
Question 7: Which of the following best describes a 'mistake-proofing' (poka-yoke) device?
- A statistical control chart monitoring process output
- A physical or electronic mechanism that prevents errors or makes them immediately obvious (Correct answer)
- A training program to reduce human error rates
- A standard operating procedure checklist
Correct answer: A physical or electronic mechanism that prevents errors or makes them immediately obvious
Poka-yoke devices are physical or electronic mechanisms designed to prevent defects from occurring or to detect them immediately when they do, making errors impossible or obvious.
Lean Six Sigma Black Belt Certification Basic 5
Which analysis technique identifies the vital few causes responsible for the majority of defects, based on the 80/20 rule?