DMAIC: Improve and Control Flashcards
7 cards from real Lean Six Sigma Green Belt Certification practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 DMAIC: Improve and Control flashcards as text
A team finds that its process average has shifted by 1.5 sigma over time. According to Lean Six Sigma convention, how does this assumption affect the reported DPMO for a Six Sigma process?
Answer: DPMO increases from near zero to 3.4
The traditional Six Sigma benchmark of 3.4 DPMO already incorporates a 1.5-sigma long-term shift, which is why a 'Six Sigma' process with no shift would yield near-zero defects.
Which type of waste in Lean is represented by producing goods before customer demand requires them?
Answer: Overproduction
Overproduction—making more than what is needed, when it is not needed—is considered the most serious waste in Lean because it generates all other wastes.
A team conducting a pilot test records these cycle times (seconds): 42, 45, 44, 43, 46, 44, 45. The spec limit is 50 seconds maximum. What is the most accurate statement?
Answer: The process appears capable, but a full capability study with more data is needed to confirm
All seven values fall well below the 50-second limit, suggesting the process may be capable, but seven data points are insufficient to calculate a reliable Cpk or confirm statistical control.
Which response surface design is most efficient for estimating a full second-order (quadratic) model with three factors?
Answer: Box-Behnken design
The Box-Behnken design estimates all linear, quadratic, and two-factor interaction terms for three or more factors using fewer runs than a central composite design and avoiding extreme corner combinations.
A control plan specifies a reaction plan of 'call supervisor.' Which improvement would make this reaction plan most effective?
Answer: Add specific, time-bound criteria for when to escalate and what containment action to take immediately
Effective reaction plans specify the immediate containment action, escalation criteria, and time frame so operators can respond consistently without ambiguity.
After implementing a process improvement, the team updates the control chart and notices that the new control limits are significantly narrower than the old ones. What does this indicate?
Answer: Process variability has been reduced by the improvement
Control limits are calculated from process variation; narrower limits indicate that within-subgroup variation has decreased, confirming the improvement reduced process spread.
A project's improvements are implemented but the process owner is resistant to maintaining the changes. What is the most effective long-term strategy?
Answer: Automate or mistake-proof the improvement so it is built into the process itself
Embedding the improvement through automation, error-proofing, or system changes makes it self-sustaining and eliminates reliance on individual compliance or behavior.