Lean Six Sigma Yellow Belt Certification Lean Six Sigma Yellow Belt The Analyze Phase 1 — Questions and Answers
Question 1: What is the primary purpose of a Pareto chart during the Analyze phase of a Lean Six Sigma project?
- To display the distribution of a single continuous variable over time
- To identify the 'vital few' causes that account for the majority of the problem (Correct answer)
- To map the flow of materials through an entire value stream
- To compare the means of two or more process groups simultaneously
Correct answer: To identify the 'vital few' causes that account for the majority of the problem
A Pareto chart applies the 80/20 rule, visually ranking causes by frequency or impact so the team can focus improvement efforts on the 'vital few' factors responsible for most of the defects or waste.
Question 2: When applying the '5 Whys' technique in the Analyze phase, what is the team ultimately trying to uncover?
- The number of defects produced in the last production run
- The root cause of a problem by repeatedly questioning each previous answer (Correct answer)
- The financial impact of the process deviation on the organization
- The statistical significance of observed data collected during Measure
Correct answer: The root cause of a problem by repeatedly questioning each previous answer
The 5 Whys is a root-cause analysis technique where each answer is challenged with another 'why,' drilling past symptoms to reveal the underlying cause that, if addressed, eliminates the problem.
Question 3: A correlation coefficient (r) of –0.92 between two variables in the Analyze phase most likely indicates:
- No meaningful relationship exists between the two variables
- A strong positive linear relationship between the two variables
- A strong negative linear relationship between the two variables (Correct answer)
- A non-linear, curved relationship between the two variables
Correct answer: A strong negative linear relationship between the two variables
A correlation coefficient close to –1 signals a strong negative (inverse) linear relationship: as one variable increases, the other decreases in a consistent, predictable pattern.
Question 4: In the Analyze phase, which type of process variation is caused by factors that are always present and built into the system itself?
- Special-cause variation
- Assignable-cause variation
- Intermittent variation
- Common-cause variation (Correct answer)
Correct answer: Common-cause variation
Common-cause variation is the natural, inherent variability of a stable process resulting from many small, random factors. Reducing it typically requires systemic process redesign, not just fixing isolated incidents.
Question 5: During the Analyze phase, an R-squared (R²) value of 0.85 in a regression model tells the team:
- 85% of the variation in the output variable is explained by the input variable(s) in the model (Correct answer)
- There is an 85% probability that the null hypothesis is true
- The process is operating within control limits 85% of the time
- 85% of defects are caused by the identified input variable
Correct answer: 85% of the variation in the output variable is explained by the input variable(s) in the model
R-squared is the coefficient of determination; it measures how much of the variability in the output (Y) is accounted for by the input(s) (X) in the regression model. An R² of 0.85 means the model explains 85% of the output's variation.
Question 6: A Lean Six Sigma team in the Analyze phase discovers that a step adds cost and time but does not change the product's form, fit, or function in any way the customer values. This step is classified as:
- Value-added activity
- Business value-added activity
- Non-value-added (waste) activity (Correct answer)
- Necessary but value-adding activity
Correct answer: Non-value-added (waste) activity
An activity is non-value-added (waste) if it consumes resources but does not transform the product in a way the customer recognizes or is willing to pay for. Eliminating such steps is a core Lean objective.
