Lean Six Sigma Green Belt Certification Lean Six Sigma Green Belt Improve Phase and Solutions 1 — Questions and Answers
Question 1: In the Improve phase, a Force Field Analysis is used primarily to:
- Map all process inputs to their corresponding outputs
- Identify and balance the driving forces and restraining forces surrounding a proposed change (Correct answer)
- Calculate the return on investment for competing solutions
- Determine the optimal factor settings through experimentation
Correct answer: Identify and balance the driving forces and restraining forces surrounding a proposed change
Force Field Analysis, developed by Kurt Lewin, visually separates the forces pushing toward a change (drivers) from those pushing against it (restrainers), helping the team plan how to amplify drivers and weaken barriers before implementation.
Question 2: Poka-Yoke devices are incorporated during the Improve phase primarily to:
- Measure process capability after a solution is deployed
- Prevent errors from occurring or detect them immediately before they become defects (Correct answer)
- Weight and rank competing improvement solutions
- Identify which input variables most strongly influence process output
Correct answer: Prevent errors from occurring or detect them immediately before they become defects
Poka-Yoke (mistake-proofing) mechanisms are designed either to make errors physically impossible (prevention) or to signal an error the instant it occurs (detection), eliminating defects at the source rather than catching them downstream.
Question 3: A full factorial designed experiment differs from a fractional factorial design in that it:
- Tests only the factor combinations most likely to affect the response
- Requires fewer experimental runs by omitting higher-order interactions
- Tests every possible combination of factor levels, estimating all main effects and all interactions (Correct answer)
- Focuses exclusively on optimizing a single critical input variable
Correct answer: Tests every possible combination of factor levels, estimating all main effects and all interactions
A full factorial design runs all possible combinations of the chosen factor levels, providing complete information on every main effect and every interaction, but at the cost of more experimental runs compared to fractional alternatives.
Question 4: When a Green Belt calculates the length of time required for cumulative project savings to equal the initial implementation cost, they are computing the:
- Net present value (NPV)
- Internal rate of return (IRR)
- Payback period (Correct answer)
- Return on investment (ROI) percentage
Correct answer: Payback period
The payback period measures how long it takes for the accumulated financial benefits of an improvement to recover its upfront cost, and is a common, easy-to-communicate financial justification metric in Lean Six Sigma projects.
Question 5: A Kaizen event conducted during the Improve phase is best characterized as:
- A multi-month statistical study to identify optimal process parameters
- A focused, short-duration team effort (typically three to five days) to rapidly implement targeted process improvements (Correct answer)
- A structured root-cause analysis session led by the process owner
- A tollgate review where the project sponsor approves the solution before piloting
Correct answer: A focused, short-duration team effort (typically three to five days) to rapidly implement targeted process improvements
Kaizen events (also called Kaizen blitzes or rapid improvement workshops) concentrate a cross-functional team on a specific process area for a brief, intensive period to design and implement improvements immediately, compressing months of change into days.
Question 6: In a designed experiment, an interaction effect between two factors (A and B) indicates that:
- Both factors individually have a statistically insignificant effect on the response
- The effect of factor A on the response variable changes depending on the level at which factor B is set (Correct answer)
- Factors A and B must remain at fixed levels for the experiment to produce valid results
- Adjusting factor A automatically and physically changes the setting of factor B
Correct answer: The effect of factor A on the response variable changes depending on the level at which factor B is set
An interaction effect means the two factors are not independent in their influence: the magnitude or direction of one factor's impact on the output shifts based on where the other factor is set, so each factor cannot be interpreted in isolation when interactions are present.
Lean Six Sigma Green Belt Certification Lean Six Sigma Green Belt Improve Phase and Solutions 1
In the Improve phase, a Force Field Analysis is used primarily to: