Lean Six Sigma Green Belt Certification DMAIC: Analyze Phase Techniques 4

Question 1

A process has a cycle time with a right-skewed distribution. Which central tendency measure best represents the typical cycle time for reporting purposes?

Accepted Answer

Median

Answer

The median is resistant to the pull of extreme high values in right-skewed distributions, making it a better measure of typical performance than the mean.

Question 2

Which tool specifically helps a team distinguish between common cause variation and special cause variation during the Analyze phase?

Accepted Answer

Control chart (SPC)

Answer

Control charts use statistical control limits to distinguish between random common cause variation and non-random special cause signals.

Question 3

A team performs a two-sample t-test comparing mean output before and after a process change and obtains p = 0.12 with α = 0.05. What action is recommended?

Accepted Answer

Fail to reject the null hypothesis; the difference is not statistically significant

Answer

Since p = 0.12 > α = 0.05, there is insufficient evidence to conclude the means differ; the null hypothesis of no difference is not rejected.

Question 4

What does it mean when a regression model's residuals show a pattern (e.g., funnel shape) when plotted against fitted values?

Accepted Answer

Heteroscedasticity exists, violating regression assumptions

Answer

A funnel-shaped residual plot indicates heteroscedasticity (non-constant variance), which violates an assumption of ordinary least squares regression.

Question 5

During an Analyze phase, a value stream map is used primarily to:

Accepted Answer

Identify non-value-added steps, wait times, and waste in the flow

Answer

Value stream mapping visually depicts material and information flow to highlight non-value-added activities, wait times, and opportunities for waste elimination.

Lean Six Sigma Green Belt Certification Practice Test

Lean Six Sigma Green Belt Certification Practice Test

Lean Six Sigma Green Belt Certification DMAIC: Analyze Phase Techniques 4