Lean Six Sigma Green Belt Control Phase
Questions, Verified Answers & Detailed Rationales
(2026/2027)
QUESTION 1
What is the primary objective of the Control phase in the DMAIC
methodology?
• A. To identify the root causes of the problem.
• B. To implement the solution and ensure the improvements are
sustained over the long term.
• C. To select the most critical project metrics.
• D. To design the experiment that proves the solution works.
Correct Answer: B. To implement the solution and ensure the
improvements are sustained over the long term.
Detailed Rationale: The Control phase is about "holding the gains." Its
goal is to create systems that prevent the process from drifting back to
its old, less efficient state.
QUESTION 2
Which of the following is the most critical document to hand off to the
process owner at the end of a project?
• A. The original project charter.
• B. The Control Plan.
, • C. The raw data collection spreadsheets.
• D. The brainstorming notes from the fishbone diagram.
Correct Answer: B. The Control Plan.
Detailed Rationale: The Control Plan is the roadmap for the process
owner; it outlines how to monitor the process, who is responsible, and
what actions to take if the process goes out of control.
QUESTION 3
What is a "Reaction Plan" in the context of a Control Plan?
• A. A list of contacts for emergency maintenance.
• B. A pre-defined set of steps to take when a process goes out of
statistical control.
• C. A summary of the team's response to management feedback.
• D. A document used to record the financial savings of the project.
Correct Answer: B. A pre-defined set of steps to take when a process
goes out of statistical control.
Detailed Rationale: Without a reaction plan, operators often do not
know what to do when an SPC chart triggers an alarm. The plan ensures
timely, corrective action is taken to prevent defects.
QUESTION 4
Which of the following is NOT a typical component of a Control Plan?
• A. Control method (e.g., SPC, inspection, checklist).
• B. Reaction plan.
• C. Sample size and frequency.
, • D. The original problem statement from the Define phase.
Correct Answer: D. The original problem statement from the Define
phase.
Detailed Rationale: While the problem statement is useful context, it is
not a working operational tool. A control plan focuses on current
parameters, measurement systems, and corrective actions.
QUESTION 5
Why is "Standardized Work" a fundamental component of the Control
phase?
• A. To increase the workload of the employees.
• B. To ensure that the best known method is performed
consistently, thereby reducing process variation.
• C. To make sure all employees have the same job title.
• D. To eliminate the need for training new hires.
Correct Answer: B. To ensure that the best known method is performed
consistently, thereby reducing process variation.
Detailed Rationale: Variation is the enemy of quality. Standardization
creates a "baseline" so that if the process fails, you know it is due to a
change in the process, not just a change in operator habit.
QUESTION 6
When updating a process control chart, what determines the frequency
of sampling?
• A. The number of operators on the shift.
, • B. The cost of the inspection.
• C. The stability of the process and the cost/risk of producing a
defect.
• D. The amount of paper available for reports.
Correct Answer: C. The stability of the process and the cost/risk of
producing a defect.
Detailed Rationale: If a process is highly unstable or produces high-cost
defects, you must sample more frequently (e.g., every hour). If the
process is highly capable and stable, you can sample less often.
QUESTION 7
In the Control phase, what is the significance of the "Owner" of the
process?
• A. The person who funded the project.
• B. The person responsible for the daily operation and
maintenance of the process after the project team disbands.
• C. The person who performs the statistical analysis.
• D. The person who writes the final report.
Correct Answer: B. The person responsible for the daily operation and
maintenance of the process after the project team disbands.
Detailed Rationale: Sustainability is impossible if the people actually
doing the work do not "own" the new process and the control
mechanisms.
QUESTION 8
Questions, Verified Answers & Detailed Rationales
(2026/2027)
QUESTION 1
What is the primary objective of the Control phase in the DMAIC
methodology?
• A. To identify the root causes of the problem.
• B. To implement the solution and ensure the improvements are
sustained over the long term.
• C. To select the most critical project metrics.
• D. To design the experiment that proves the solution works.
Correct Answer: B. To implement the solution and ensure the
improvements are sustained over the long term.
Detailed Rationale: The Control phase is about "holding the gains." Its
goal is to create systems that prevent the process from drifting back to
its old, less efficient state.
QUESTION 2
Which of the following is the most critical document to hand off to the
process owner at the end of a project?
• A. The original project charter.
• B. The Control Plan.
, • C. The raw data collection spreadsheets.
• D. The brainstorming notes from the fishbone diagram.
Correct Answer: B. The Control Plan.
Detailed Rationale: The Control Plan is the roadmap for the process
owner; it outlines how to monitor the process, who is responsible, and
what actions to take if the process goes out of control.
QUESTION 3
What is a "Reaction Plan" in the context of a Control Plan?
• A. A list of contacts for emergency maintenance.
• B. A pre-defined set of steps to take when a process goes out of
statistical control.
• C. A summary of the team's response to management feedback.
• D. A document used to record the financial savings of the project.
Correct Answer: B. A pre-defined set of steps to take when a process
goes out of statistical control.
Detailed Rationale: Without a reaction plan, operators often do not
know what to do when an SPC chart triggers an alarm. The plan ensures
timely, corrective action is taken to prevent defects.
QUESTION 4
Which of the following is NOT a typical component of a Control Plan?
• A. Control method (e.g., SPC, inspection, checklist).
• B. Reaction plan.
• C. Sample size and frequency.
, • D. The original problem statement from the Define phase.
Correct Answer: D. The original problem statement from the Define
phase.
Detailed Rationale: While the problem statement is useful context, it is
not a working operational tool. A control plan focuses on current
parameters, measurement systems, and corrective actions.
QUESTION 5
Why is "Standardized Work" a fundamental component of the Control
phase?
• A. To increase the workload of the employees.
• B. To ensure that the best known method is performed
consistently, thereby reducing process variation.
• C. To make sure all employees have the same job title.
• D. To eliminate the need for training new hires.
Correct Answer: B. To ensure that the best known method is performed
consistently, thereby reducing process variation.
Detailed Rationale: Variation is the enemy of quality. Standardization
creates a "baseline" so that if the process fails, you know it is due to a
change in the process, not just a change in operator habit.
QUESTION 6
When updating a process control chart, what determines the frequency
of sampling?
• A. The number of operators on the shift.
, • B. The cost of the inspection.
• C. The stability of the process and the cost/risk of producing a
defect.
• D. The amount of paper available for reports.
Correct Answer: C. The stability of the process and the cost/risk of
producing a defect.
Detailed Rationale: If a process is highly unstable or produces high-cost
defects, you must sample more frequently (e.g., every hour). If the
process is highly capable and stable, you can sample less often.
QUESTION 7
In the Control phase, what is the significance of the "Owner" of the
process?
• A. The person who funded the project.
• B. The person responsible for the daily operation and
maintenance of the process after the project team disbands.
• C. The person who performs the statistical analysis.
• D. The person who writes the final report.
Correct Answer: B. The person responsible for the daily operation and
maintenance of the process after the project team disbands.
Detailed Rationale: Sustainability is impossible if the people actually
doing the work do not "own" the new process and the control
mechanisms.
QUESTION 8
