Lean Six Sigma Green Belt Certification Measure Phase and Statistics 3 — Questions and Answers
Question 1: In hypothesis testing, what does a p-value of 0.03 indicate when the significance level (α) is 0.05?
- Fail to reject the null hypothesis
- Reject the null hypothesis (Correct answer)
- The test is inconclusive
- The sample size is insufficient
Correct answer: Reject the null hypothesis
When p-value (0.03) < α (0.05), we reject the null hypothesis, concluding there is a statistically significant effect.
Question 2: What is the primary purpose of a Process Failure Mode and Effects Analysis (PFMEA) in the Measure phase?
- To identify and prioritize potential failure modes before they occur (Correct answer)
- To document current process performance
- To calculate process sigma level
- To design the data collection plan
Correct answer: To identify and prioritize potential failure modes before they occur
PFMEA proactively identifies potential failure modes, their effects, and causes to prioritize risk reduction efforts.
Question 3: Which statistic is most resistant to the influence of outliers when describing the center of a dataset?
- Mean
- Median (Correct answer)
- Mode
- Variance
Correct answer: Median
The median is resistant to outliers because it is based on rank order, not the actual values of extreme data points.
Question 4: A Pareto chart is used in the Measure phase primarily to:
- Determine process capability
- Identify the vital few causes contributing to most defects (Correct answer)
- Map process flow
- Establish measurement system validity
Correct answer: Identify the vital few causes contributing to most defects
Pareto charts apply the 80/20 rule to visually identify the few categories that account for the majority of problems.
Question 5: What is the Z-score for a data point that is 2 standard deviations below the mean?
- +2
- -2 (Correct answer)
- 0.02
- -0.2
Correct answer: -2
Z = (X - μ) / σ; a value 2 standard deviations below the mean yields Z = -2.
Question 6: Which type of data collection error occurs when inspectors change their rating criteria over time?
- Appraiser bias
- Instrument drift
- Criteria drift (Correct answer)
- Sampling bias
Correct answer: Criteria drift
Criteria drift happens when the standards or interpretation used for measurement gradually shift during a study.
Question 7: When using a check sheet during the Measure phase, what is its primary function?
- To track project milestones
- To systematically collect and tally defect occurrence data (Correct answer)
- To calculate process sigma
- To map the value stream
Correct answer: To systematically collect and tally defect occurrence data
Check sheets provide a structured form for real-time, consistent recording and tallying of event occurrences at the source.
Lean Six Sigma Green Belt Certification Measure Phase and Statistics 3
In hypothesis testing, what does a p-value of 0.03 indicate when the significance level (α) is 0.05?