Lean Six Sigma Green Belt Control Phase and Sustainment Questions and Answers — Questions and Answers
Question 1: What is the primary purpose of the Control Phase in a DMAIC project?
- To lock in the gains and ensure the improved process is sustained. (Correct answer)
- To identify the root causes of process variation using statistical tools.
- To brainstorm and implement a wide range of potential solutions.
- To validate the measurement system's accuracy and reliability.
Correct answer: To lock in the gains and ensure the improved process is sustained.
The primary purpose of the Control Phase is to ensure that the improvements made in the 'Improve' phase are maintained over the long term. This involves creating monitoring systems, standardizing the new process, and transferring ownership.
Question 2: A project team implemented a new stocking procedure to reduce order fulfillment time. To monitor the new process and ensure it remains stable, they track the average fulfillment time daily. Which tool is most appropriate for this task?
- Fishbone Diagram
- Pareto Chart
- Statistical Process Control (SPC) Chart (Correct answer)
- Failure Mode and Effects Analysis (FMEA)
Correct answer: Statistical Process Control (SPC) Chart
Statistical Process Control (SPC) charts are specifically designed to monitor process performance over time, distinguish between common cause and special cause variation, and detect when a process is becoming unstable.
Question 3: Which of the following is the MOST critical component of a comprehensive Control Plan?
- A response plan for out-of-control conditions. (Correct answer)
- A list of all team members and stakeholders.
- The initial process capability analysis from the Measure phase.
- A detailed summary of the brainstorming sessions from the Improve phase.
Correct answer: A response plan for out-of-control conditions.
While a Control Plan documents what to monitor and how, its most critical element is the response or reaction plan. This plan details the specific actions to be taken by responsible personnel when the process shows signs of being out of control, ensuring that deviations are addressed promptly before they become major problems.
Question 4: A Green Belt project to reduce invoicing errors has successfully concluded, and the improved process is stable. What is the final, crucial step to ensure long-term sustainment of the gains?
- Recalculating the project's ROI for the final presentation.
- Formally transferring ownership to the process owner with a documented control plan. (Correct answer)
- Conducting one final Design of Experiments to re-verify the results.
- Writing a press release to celebrate the project's success.
Correct answer: Formally transferring ownership to the process owner with a documented control plan.
Long-term sustainment depends on clear accountability. The project team must formally hand off the improved process to the process owner, who is responsible for its day-to-day management. This transfer includes providing all necessary documentation, especially the control plan, to enable the owner to monitor and maintain the process effectively.
Question 5: A manufacturing team has implemented a new assembly sequence that is more ergonomic and efficient. To ensure all operators, including new hires, perform the task consistently according to the improved method, what document should be created or updated?
- A project storyboard
- A stakeholder analysis
- Standard Operating Procedures (SOPs) (Correct answer)
- A Pugh matrix
Correct answer: Standard Operating Procedures (SOPs)
Standard Operating Procedures (SOPs) provide detailed, step-by-step instructions for performing a task. Updating or creating SOPs is a fundamental activity in the Control phase to ensure the new, improved method is standardized and consistently followed by everyone.
Question 6: An X-bar and R chart is being used to monitor the average diameter of a machined part. The process owner observes six consecutive points trending downwards, but all points are still within the control limits. According to standard SPC rules, what is the correct interpretation?
- The process is perfectly stable and requires no action.
- This pattern indicates a special cause of variation that should be investigated. (Correct answer)
- The control limits should be immediately recalculated based on the new trend.
- The measurement system is likely broken and must be replaced.
Correct answer: This pattern indicates a special cause of variation that should be investigated.
In Statistical Process Control (SPC), certain patterns or 'runs' signal the presence of a special cause of variation, even if no points have crossed the control limits. A run of six or more consecutive points trending in the same direction is a classic rule indicating that a non-random factor is influencing the process, which warrants investigation.
Lean Six Sigma Green Belt Control Phase and Sustainment Questions and Answers
What is the primary purpose of the Control Phase in a DMAIC project?