Lean Six Sigma Yellow Belt Certification The Measure Phase 2 — Questions and Answers
Question 1: Which type of data is collected when you record whether a product passes or fails inspection?
- Continuous data
- Attribute data (Correct answer)
- Variable data
- Discrete ratio data
Correct answer: Attribute data
Attribute data (also called discrete data) classifies items into categories such as pass/fail or defective/non-defective.
Question 2: A control chart shows a process with all points within control limits but 9 consecutive points on the same side of the centerline. This indicates:
- The process is in statistical control
- A special cause of variation is present (Correct answer)
- Common cause variation only
- The control limits need to be recalculated
Correct answer: A special cause of variation is present
Nine or more consecutive points on one side of the centerline is a Western Electric rule violation indicating a special cause of variation.
Question 3: What does the 'sigma level' of a process primarily indicate?
- The average cycle time of the process
- How many defects occur per million opportunities (Correct answer)
- The number of process steps
- The cost of quality
Correct answer: How many defects occur per million opportunities
Sigma level indicates process capability expressed as defects per million opportunities (DPMO), with higher sigma meaning fewer defects.
Question 4: In a Gauge R&R study, 'reproducibility' refers to variation caused by:
- The measurement instrument itself
- Different operators measuring the same part (Correct answer)
- Part-to-part variation
- Environmental conditions
Correct answer: Different operators measuring the same part
Reproducibility measures the variation in average measurements made by different operators using the same gauge on the same part.
Question 5: Which sampling method divides the population into subgroups and randomly samples from each subgroup?
- Simple random sampling
- Systematic sampling
- Stratified sampling (Correct answer)
- Convenience sampling
Correct answer: Stratified sampling
Stratified sampling divides the population into homogeneous subgroups (strata) and takes random samples from each stratum.
Question 6: A process produces 150 defects in 500 units where each unit has 10 opportunities for defects. What is the DPO?
- 0.03 (Correct answer)
- 0.30
- 0.015
- 0.15
Correct answer: 0.03
DPO = Defects / (Units × Opportunities) = 150 / (500 × 10) = 150 / 5000 = 0.03.
Question 7: What is the primary purpose of a time-series plot (run chart) in the Measure phase?
- To identify the root cause of a defect
- To display process data over time and detect trends or shifts (Correct answer)
- To calculate process capability indices
- To compare the means of two processes
Correct answer: To display process data over time and detect trends or shifts
A run chart plots data points in time order to reveal trends, shifts, cycles, or other non-random patterns in process performance.
