ASQ Six Sigma Green Belt 3 — Questions and Answers
Question 1: In Design of Experiments (DOE), what is a 'main effect'?
- The interaction between two or more factors
- The average change in the response when a factor moves from its low to high level (Correct answer)
- The residual error not explained by any factor
- The curvature detected in a response surface
Correct answer: The average change in the response when a factor moves from its low to high level
A main effect is the average impact of a single factor on the response variable, independent of other factors.
Question 2: Which control chart is most appropriate for monitoring the number of defects per unit when the sample size varies?
- p-chart
- c-chart
- u-chart (Correct answer)
- np-chart
Correct answer: u-chart
The u-chart tracks the average number of defects per unit and is designed to handle varying subgroup sizes.
Question 3: A team uses a Pugh Concept Selection Matrix. What is its primary purpose in the Improve phase?
- To quantify the financial impact of proposed solutions
- To systematically compare solution alternatives against selection criteria (Correct answer)
- To establish the timeline for implementing improvements
- To identify risks associated with the current process
Correct answer: To systematically compare solution alternatives against selection criteria
The Pugh matrix evaluates solution alternatives relative to a reference concept across multiple weighted criteria, guiding objective solution selection.
Question 4: What is the relationship between confidence level and significance level (alpha) in hypothesis testing?
- Confidence level = 1 - alpha (Correct answer)
- Confidence level = alpha
- Confidence level = alpha / 2
- Confidence level = 1 + alpha
Correct answer: Confidence level = 1 - alpha
A 95% confidence level corresponds to a 5% significance level (alpha = 0.05), since confidence level = 1 − alpha.
Question 5: In a scatter diagram showing a strong positive correlation, what does this indicate?
- As X increases, Y decreases proportionally
- Changes in X cause changes in Y
- As X increases, Y also tends to increase (Correct answer)
- X and Y are independent of each other
Correct answer: As X increases, Y also tends to increase
A positive correlation means X and Y move in the same direction, though correlation does not establish causation.
Question 6: What distinguishes common cause variation from special cause variation?
- Common cause is unpredictable while special cause is predictable
- Common cause is inherent to the process; special cause is due to specific assignable factors (Correct answer)
- Common cause always results in more defects than special cause
- Special cause variation only occurs in manufacturing processes
Correct answer: Common cause is inherent to the process; special cause is due to specific assignable factors
Common cause variation is the natural, random variation built into the system, while special cause variation stems from identifiable assignable factors.
Question 7: Which Six Sigma metric expresses defect rate in terms of opportunities for defects rather than units?
- Defects Per Unit (DPU)
- Defects Per Million Opportunities (DPMO) (Correct answer)
- Rolled Throughput Yield (RTY)
- First Pass Yield (FPY)
Correct answer: Defects Per Million Opportunities (DPMO)
DPMO normalizes the defect rate by the number of opportunities per unit, allowing fair comparison across processes with different complexity levels.
ASQ Six Sigma Green Belt 3
In Design of Experiments (DOE), what is a 'main effect'?