Control Phase: Free CSSBB Practice Questions

Question 1

What is the primary purpose of a control chart in the ongoing evaluation and monitoring phase of a Lean Six Sigma project?

To track project financial savings and validate that cost reduction targets are sustained over time To detect common cause variation and ensure that process mean stays centered on the target value To detect special cause variation and signal when a process shifts out of statistical control To measure overall process capability indices and confirm that Cpk values remain above specification limits

Correct Answer: To detect special cause variation and signal when a process shifts out of statistical control

The primary purpose of a control chart is to distinguish between special cause variation (assignable, unusual signals) and common cause variation (inherent process noise), alerting practitioners when a process has shifted out of statistical control so corrective action can be taken.

Measuring process capability indices like Cpk is a separate analysis typically done during the Analyze or post-improvement phase, not the ongoing monitoring function of the chart itself. Tracking financial savings is a project management activity, not a statistical process control function. Control charts do not detect common cause variation as a signal; common cause variation is the expected baseline noise the chart treats as normal.

Key concept tested: the fundamental purpose of Statistical Process Control charts in the Control phase.

Question 2

What is the primary purpose of visual controls in Lean Six Sigma?

To document standard operating procedures for each workstation To make process performance data accessible through detailed reports To make workplace conditions and deviations obvious to all employees quickly To make process status and abnormalities visible at a glance

Correct Answer: To make process status and abnormalities visible at a glance

The correct answer captures the primary purpose of visual controls: making process status and abnormalities immediately visible at a glance, enabling rapid identification of normal versus abnormal conditions without requiring detailed analysis.

Documenting standard operating procedures is the purpose of SOPs, not visual controls specifically. Making data accessible through detailed reports contradicts the "at a glance" nature of visual controls, which are designed to eliminate the need for detailed reports. Making workplace conditions and deviations obvious to all employees quickly is very close and arguably also correct, but the best answer emphasizes "process status and abnormalities" which is more precisely aligned with how visual controls function in Lean Six Sigma, particularly in concepts like andon systems and kanban boards.

Key concept tested: the role of visual management in enabling immediate status recognition and abnormality detection.

Question 3

What does the acronym SPC stand for in the context of ongoing evaluation and monitoring?

Standard Process Control methodology Systematic Process Charting Statistical Process Control Statistical Performance Capability

Correct Answer: Statistical Process Control

Statistical Process Control (SPC) is the correct term, referring to the use of statistical methods such as control charts to monitor and control a process over time, ensuring it operates at its full potential and detecting variation before it leads to defects.

Statistical Performance Capability is not a recognized acronym; process capability uses metrics like Cp and Cpk but is not called SPC. Systematic Process Charting is a fabricated term that does not correspond to any standard Lean Six Sigma methodology. Standard Process Control methodology incorrectly substitutes Standard for Statistical, which is the defining characteristic of SPC.

The key concept tested is knowledge of SPC as a fundamental Control phase tool for ongoing process monitoring.

Control Phase

CSSBB - Control Phase Example Questions

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