Lean Six Sigma Green Belt Certification Certified Six Sigma Green Belt 1

Question 1

What distinguishes common cause variation from special cause variation in a process?

Accepted Answer

Common cause variation is inherent and systemic to the process, while special cause variation stems from assignable, external factors

Answer

Common cause (or random) variation is the natural, built-in noise of a stable process and can only be reduced by changing the system itself. Special cause variation is triggered by identifiable, assignable factors outside the normal process and requires targeted investigation and removal.

Question 2

In a simple linear regression model, what does the coefficient of determination (R²) represent?

Accepted Answer

The proportion of total variance in the response variable that is explained by the predictor variable

Answer

R² ranges from 0 to 1 and quantifies how much of the variability in Y is accounted for by its linear relationship with X. An R² of 0.85, for example, means 85% of Y's variation is explained by the model, leaving 15% unexplained.

Question 3

What is the primary purpose of conducting a Gage Repeatability and Reproducibility (Gage R&R) study?

Accepted Answer

To quantify how much of the observed process variation is attributable to the measurement system itself

Answer

A Gage R&R study partitions total observed variation into process variation and measurement system variation (repeatability = equipment variation, reproducibility = appraiser-to-appraiser variation). If the measurement system contributes too large a share, the data used for decisions is unreliable.

Question 4

Which of the following best describes a key deliverable of the Measure phase in DMAIC?

Accepted Answer

A baseline process capability or sigma level that quantifies current performance

Answer

The Measure phase establishes a data-driven baseline — capturing how the process performs today before any changes are made. This baseline (often expressed as Cpk, DPMO, or sigma level) becomes the benchmark against which Improve-phase gains are measured.

Question 5

In Design of Experiments (DOE), what is a 'main effect'?

Accepted Answer

The average change in the response variable when a single factor moves from its low level to its high level

Answer

A main effect measures the individual impact of one factor on the response, averaged across all levels of the other factors. It is distinct from an interaction effect, which occurs when the effect of one factor depends on the level of another factor.

Lean Six Sigma Green Belt Certification Practice Test

Lean Six Sigma Green Belt Certification Practice Test

Lean Six Sigma Green Belt Certification Certified Six Sigma Green Belt 1