Six Sigma Green Belt Flashcards

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

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

A main effect is the average impact of a single factor on the response variable, independent of other factors.

Which control chart is most appropriate for monitoring the number of defects per unit when the sample size varies?

Answer: u-chart

The u-chart tracks the average number of defects per unit and is designed to handle varying subgroup sizes.

A team uses a Pugh Concept Selection Matrix. What is its primary purpose in the Improve phase?

Answer: To systematically compare solution alternatives against selection criteria

The Pugh matrix evaluates solution alternatives relative to a reference concept across multiple weighted criteria, guiding objective solution selection.

What is the relationship between confidence level and significance level (alpha) in hypothesis testing?

Answer: Confidence level = 1 - alpha

A 95% confidence level corresponds to a 5% significance level (alpha = 0.05), since confidence level = 1 − alpha.

In a scatter diagram showing a strong positive correlation, what does this indicate?

Answer: As X increases, Y also tends to increase

A positive correlation means X and Y move in the same direction, though correlation does not establish causation.

What distinguishes common cause variation from special cause variation?

Answer: Common cause is inherent to the process; special cause is due to specific assignable factors

Common cause variation is the natural, random variation built into the system, while special cause variation stems from identifiable assignable factors.

Which Six Sigma metric expresses defect rate in terms of opportunities for defects rather than units?

Answer: Defects Per Million Opportunities (DPMO)

DPMO normalizes the defect rate by the number of opportunities per unit, allowing fair comparison across processes with different complexity levels.