Lean Six Sigma Yellow Belt Certification Lean Six Sigma Yellow Belt Control and Sustainment Methods 1

Question 1

What is the primary purpose of a Control Plan in the Control phase of DMAIC?

Accepted Answer

To specify what process variables to monitor, how to measure them, the sampling frequency, and the response if limits are exceeded

Answer

A Control Plan is a structured document that defines which key inputs and outputs to monitor, the measurement method and frequency, acceptable limits, and the required response action when a process goes out of control — ensuring improvements are maintained.

Question 2

Which type of control chart is most appropriate for tracking the number of defects found in a fixed-size sample?

Accepted Answer

c-chart

Answer

The c-chart (count chart) is used when counting the number of defects (nonconformities) per unit when the sample size is constant. The p-chart tracks the proportion defective, while X-bar/R and I-MR charts are used for continuous measurement data.

Question 3

In Statistical Process Control, a process is said to exhibit 'common cause variation' when:

Accepted Answer

The process shows consistent, random variation within control limits with no non-random patterns

Answer

Common cause variation is the natural, inherent variability in a stable process — data points fluctuate randomly within the control limits. Special cause variation, by contrast, produces non-random patterns such as runs, trends, or points outside control limits.

Question 4

Mistake-proofing (poka-yoke) is most accurately described as:

Accepted Answer

Redesigning the process or equipment so that errors are physically impossible or immediately detected and flagged

Answer

Poka-yoke devices or design changes prevent errors at the source by making incorrect actions impossible (prevention) or by immediately signaling when an error occurs (detection). It is a stronger control mechanism than training or inspection alone.

Question 5

When a control chart signals an out-of-control condition, what should the process operator do first?

Accepted Answer

Follow the pre-defined reaction plan documented in the Control Plan

Answer

A reaction (or response) plan is established during the Control phase precisely for this scenario. It tells operators the immediate containment steps to take when an out-of-control signal appears, ensuring a fast, consistent response without waiting for management or starting a lengthy analysis.

Lean Six Sigma Yellow Belt Certification Practice Test

Lean Six Sigma Yellow Belt Certification Practice Test

Lean Six Sigma Yellow Belt Certification Lean Six Sigma Yellow Belt Control and Sustainment Methods 1