DMAIC: Improve and Control 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: Improve and Control flashcards as text
A Lean Six Sigma team uses a 2^3 full factorial experiment with center points. What is the primary reason for adding center points?
Answer: To detect curvature in the response and estimate pure error
Center points are added to a factorial design to test for curvature (non-linearity) in the response surface and provide an estimate of pure experimental error.
Which control chart is most appropriate for monitoring the fraction of defective units in large, variable-sized subgroups?
Answer: p-chart
The p-chart tracks the proportion defective and accommodates varying subgroup sizes, unlike the np-chart which requires a constant subgroup size.
During the Control phase, an operator notices a trend of seven consecutive points rising on an X-bar chart but all within control limits. What is the correct response?
Answer: Investigate for a special cause because a run of seven in one direction is a non-random pattern
Western Electric rules recognize that seven consecutive points trending in one direction is a non-random signal of a special cause, even if all points remain within the three-sigma control limits.
A team implements a 5S program as part of the Improve phase. Which pillar directly reduces search time by assigning a designated location to every item?
Answer: Set in Order (Seiton)
Set in Order (Seiton) assigns and visually marks a specific location for each item so workers can find and return it without searching.
What statistical method is used to confirm that a process improvement resulted in a statistically significant change in the process mean?
Answer: Hypothesis test (e.g., t-test or ANOVA)
A hypothesis test such as a two-sample t-test or ANOVA formally evaluates whether the observed difference in means before and after improvement is statistically significant.
In a response surface methodology (RSM) experiment, what is the purpose of a 'steepest ascent' path?
Answer: To move efficiently toward the region of optimal response between screening and optimization runs
The method of steepest ascent uses the gradient of a first-order model to guide sequential experiments toward the optimal region before fitting a higher-order surface.
A Standard Operating Procedure (SOP) is revised after a process improvement. Which action best ensures operators consistently follow the updated SOP?
Answer: Conduct documented training and verify competency through observation
Documented training with competency verification confirms that operators understand and can perform the updated procedure, closing the gap between having documentation and actually executing it.