CPS Analysis & Optimization 2 — Questions and Answers
Question 1: A process analyst observes that cycle time varies widely between shifts despite identical procedures. Which analysis technique best identifies the root cause?
- Pareto analysis
- Multi-vari study (Correct answer)
- Failure Mode and Effects Analysis
- Value stream mapping
Correct answer: Multi-vari study
A multi-vari study isolates sources of variation across time, units, and within-unit factors to pinpoint where variability originates.
Question 2: When performing a value stream map, which metric directly measures the ratio of value-added time to total lead time?
- Process cycle efficiency (Correct answer)
- Takt time ratio
- First pass yield
- Overall equipment effectiveness
Correct answer: Process cycle efficiency
Process cycle efficiency (PCE) equals value-added time divided by total lead time, revealing waste proportion in the flow.
Question 3: A team wants to reduce defects but has limited resources. Which approach ensures effort targets the highest-impact defect categories first?
- Scatter diagram
- Control chart
- Pareto analysis (Correct answer)
- Histogram
Correct answer: Pareto analysis
Pareto analysis applies the 80/20 rule to rank defect categories by frequency or cost, directing resources to the vital few causes.
Question 4: In regression analysis for process optimization, what does an R² value of 0.92 indicate?
- 92% of the data points are outliers
- The model explains 92% of the variation in the output (Correct answer)
- There is a 92% chance the process is in control
- 92% of inputs are statistically significant
Correct answer: The model explains 92% of the variation in the output
R² represents the coefficient of determination, indicating what proportion of output variance is explained by the regression model.
Question 5: Which lean concept specifically targets eliminating wait time between consecutive process steps?
- Single-piece flow (Correct answer)
- Kaizen burst
- 5S methodology
- Poka-yoke
Correct answer: Single-piece flow
Single-piece flow moves one unit at a time between steps, eliminating batch queuing and the waiting waste it creates.
Question 6: A CPS practitioner needs to determine whether two process changes together produce an effect greater than either alone. Which experimental design detects this?
- One-factor-at-a-time testing
- Factorial design (Correct answer)
- Gauge R&R study
- Run chart analysis
Correct answer: Factorial design
Factorial designs test multiple factors simultaneously and can detect interaction effects between factors that one-at-a-time testing misses.
Question 7: Process capability index Cpk differs from Cp in which critical way?
- Cpk uses control limits while Cp uses specification limits
- Cpk accounts for process centering while Cp only measures spread (Correct answer)
- Cpk applies to attributes data while Cp applies to variables data
- Cpk is used for short-term studies while Cp is for long-term
Correct answer: Cpk accounts for process centering while Cp only measures spread
Cpk incorporates the distance from the process mean to the nearest specification limit, penalizing off-center processes that Cp ignores.
CPS Analysis & Optimization 2
A process analyst observes that cycle time varies widely between shifts despite identical procedures.
Which analysis technique best identifies the root cause?