DMAIC: Analyze Phase Techniques Flashcards
7 cards from real Lean Six Sigma Green Belt Certification practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 DMAIC: Analyze Phase Techniques flashcards as text
A process has a cycle time with a right-skewed distribution. Which central tendency measure best represents the typical cycle time for reporting purposes?
Answer: Median
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.
Which tool specifically helps a team distinguish between common cause variation and special cause variation during the Analyze phase?
Answer: Control chart (SPC)
Control charts use statistical control limits to distinguish between random common cause variation and non-random special cause signals.
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?
Answer: Fail to reject the null hypothesis; the difference is not statistically significant
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.
What does it mean when a regression model's residuals show a pattern (e.g., funnel shape) when plotted against fitted values?
Answer: Heteroscedasticity exists, violating regression assumptions
A funnel-shaped residual plot indicates heteroscedasticity (non-constant variance), which violates an assumption of ordinary least squares regression.
During an Analyze phase, a value stream map is used primarily to:
Answer: Identify non-value-added steps, wait times, and waste in the flow
Value stream mapping visually depicts material and information flow to highlight non-value-added activities, wait times, and opportunities for waste elimination.
A Green Belt is analyzing data and finds that the X variable explains very little of the variation in Y. The scatter plot shows random scatter. What is the MOST likely conclusion?
Answer: The X variable has little to no linear relationship with Y
Random scatter with low R² indicates the X variable does not linearly explain Y's variation, suggesting it is not a key process input variable for this outcome.
In a cause-and-effect matrix, which inputs receive the highest priority for further investigation?
Answer: Inputs with the highest weighted score based on correlation to key outputs
A cause-and-effect matrix prioritizes inputs by multiplying their correlation ratings to each output by the output's importance weight, then summing across outputs.