Lean Six Sigma Green Belt Certification DMAIC: Measure Phase Tools 5

Question 1

A Green Belt plots an X-bar chart and notices that all sample means fall within the control limits but 90% cluster tightly near the centerline. What is the most likely cause?

Accepted Answer

The control limits are too wide relative to the actual process variation

Answer

When points cluster too closely to the centerline, the control limits were likely calculated from inflated variation estimates, making them too wide to detect real signals.

Question 2

Which formula correctly expresses the relationship between total observed variation, process variation, and measurement system variation?

Accepted Answer

σ²_total = σ²_process + σ²_measurement

Answer

Variances from independent sources are additive; total observed variance equals the sum of process variance and measurement system variance.

Question 3

A practitioner uses an attribute agreement analysis with three appraisers and 50 parts. What is the primary output being evaluated?

Accepted Answer

The consistency of appraisers in classifying parts as pass/fail or by category

Answer

Attribute agreement analysis evaluates how consistently appraisers agree with each other and with a reference standard when making categorical (attribute) judgments.

Question 4

In a time series plot of daily defect counts, a practitioner observes a consistent upward trend over 20 days. This pattern most likely indicates:

Accepted Answer

A special cause is systematically affecting the process over time

Answer

A sustained directional trend in a time series plot is a non-random pattern that indicates a special cause (e.g., tool wear, material degradation) is systematically shifting the process.

Question 5

When calculating sigma level from a DPMO value, a Green Belt must account for the 1.5-sigma shift convention because:

Accepted Answer

It is a standard assumption that long-term process mean shifts by approximately 1.5 sigma from the short-term mean

Answer

The 1.5-sigma shift is a convention established by Motorola to account for the typical long-term drift of a process mean relative to its short-term capability.

Lean Six Sigma Green Belt Certification Practice Test

Lean Six Sigma Green Belt Certification Practice Test

Lean Six Sigma Green Belt Certification DMAIC: Measure Phase Tools 5