ASQ Six Sigma Green Belt 2 — Questions and Answers
Question 1: In Six Sigma, what does the term 'sigma level' measure?
- The number of defects per unit produced
- The number of standard deviations between the process mean and the nearest specification limit (Correct answer)
- The percentage of variation explained by the X variables
- The ratio of tolerance to process spread
Correct answer: The number of standard deviations between the process mean and the nearest specification limit
Sigma level indicates how many standard deviations fit between the process mean and the nearest specification limit, reflecting process capability.
Question 2: Which tool is used in the Define phase to identify all stakeholders and their requirements for a Six Sigma project?
- SIPOC diagram (Correct answer)
- Control chart
- Failure Mode and Effects Analysis (FMEA)
- Fishbone diagram
Correct answer: SIPOC diagram
The SIPOC diagram maps Suppliers, Inputs, Process, Outputs, and Customers, helping define project scope and stakeholder requirements during the Define phase.
Question 3: What is the purpose of a Gage R&R study in the Measure phase?
- To identify root causes of defects
- To evaluate the repeatability and reproducibility of a measurement system (Correct answer)
- To establish baseline process capability
- To prioritize potential causes using a Pareto chart
Correct answer: To evaluate the repeatability and reproducibility of a measurement system
Gage R&R quantifies how much of the observed process variation is due to measurement error versus actual process variation.
Question 4: A process has a Cp of 1.5 but a Cpk of 0.8. What does this indicate?
- The process spread is too wide relative to the specification
- The process is centered within specifications but has too much variation
- The process has adequate potential but is not centered within the specification limits (Correct answer)
- The process is both centered and capable
Correct answer: The process has adequate potential but is not centered within the specification limits
Cp measures process spread potential while Cpk accounts for centering; a high Cp with low Cpk means the process could be capable if properly centered.
Question 5: In hypothesis testing, a Type II error (beta error) occurs when:
- A true null hypothesis is rejected
- A false null hypothesis is not rejected (Correct answer)
- The p-value exceeds the significance level
- The confidence interval includes zero
Correct answer: A false null hypothesis is not rejected
A Type II error (beta error) is failing to detect a real effect — accepting the null hypothesis when it is actually false.
Question 6: Which of the following best describes the purpose of stratification in data analysis?
- Separating data into subgroups to identify patterns or sources of variation (Correct answer)
- Ranking defects from most to least frequent
- Plotting data over time to detect trends
- Establishing control limits for a process
Correct answer: Separating data into subgroups to identify patterns or sources of variation
Stratification divides data into meaningful subgroups (by shift, machine, operator, etc.) to reveal hidden patterns and root causes of variation.
Question 7: What is the primary output of the Analyze phase in DMAIC?
- A list of potential solutions ranked by feasibility
- Validated root causes of the problem (Correct answer)
- Updated control plans and standard operating procedures
- Baseline measurements of current process performance
Correct answer: Validated root causes of the problem
The Analyze phase uses statistical and graphical tools to identify and validate the root causes that explain the performance gap defined in earlier phases.
ASQ Six Sigma Green Belt 2
In Six Sigma, what does the term 'sigma level' measure?