Lean Six Sigma Green Belt Certification DMAIC: Improve and Control 5

Question 1

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?

Accepted Answer

DPMO increases from near zero to 3.4

Answer

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.

Question 2

Which type of waste in Lean is represented by producing goods before customer demand requires them?

Accepted Answer

Overproduction

Answer

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.

Question 3

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?

Accepted Answer

The process appears capable, but a full capability study with more data is needed to confirm

Answer

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.

Question 4

Which response surface design is most efficient for estimating a full second-order (quadratic) model with three factors?

Accepted Answer

Box-Behnken design

Answer

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.

Question 5

A control plan specifies a reaction plan of 'call supervisor.' Which improvement would make this reaction plan most effective?

Accepted Answer

Add specific, time-bound criteria for when to escalate and what containment action to take immediately

Answer

Effective reaction plans specify the immediate containment action, escalation criteria, and time frame so operators can respond consistently without ambiguity.

Lean Six Sigma Green Belt Certification Practice Test

Lean Six Sigma Green Belt Certification Practice Test

Lean Six Sigma Green Belt Certification DMAIC: Improve and Control 5