Lean Six Sigma Yellow Belt Certification Measure Phase Tools 4 — Questions and Answers
Question 1: When a process has a Cpk value significantly lower than its Cp value, this indicates that the process:
- Has too much variation relative to specifications
- Is not centered between the specification limits (Correct answer)
- Is running at exactly six-sigma quality
- Has insufficient data for analysis
Correct answer: Is not centered between the specification limits
Cpk accounts for process centering; a Cpk much lower than Cp signals the process mean is shifted toward one of the specification limits.
Question 2: Which of the following best describes 'common cause variation' in a process?
- Variation from a single identifiable special event
- Random, inherent variation present in every stable process (Correct answer)
- Variation caused by a new machine or operator error
- Variation that always produces out-of-specification product
Correct answer: Random, inherent variation present in every stable process
Common cause variation is the natural, predictable noise in a stable process and can only be reduced by changing the process itself.
Question 3: A process map differs from a SIPOC because it:
- Identifies customers and suppliers but not process steps
- Shows detailed, step-by-step activities including decision points and loops (Correct answer)
- Is used only during the Control phase
- Focuses exclusively on data collection plans
Correct answer: Shows detailed, step-by-step activities including decision points and loops
A process map (flowchart) captures granular steps, decisions, and flow paths, providing far more detail than the high-level SIPOC overview.
Question 4: In a data collection plan, 'stratification' means:
- Randomly sampling data from the entire population
- Grouping data by category (e.g., shift, machine) to reveal hidden patterns (Correct answer)
- Converting attribute data into continuous measurements
- Eliminating outliers before performing analysis
Correct answer: Grouping data by category (e.g., shift, machine) to reveal hidden patterns
Stratification splits data into meaningful subgroups so that differences between groups — not just overall averages — can be detected.
Question 5: What does 'percent gage R&R' measure in a measurement system analysis?
- The percentage of parts that pass inspection
- The percentage of total observed variation attributable to the measurement system (Correct answer)
- The percentage of operators who were trained correctly
- The proportion of parts measured within specification limits
Correct answer: The percentage of total observed variation attributable to the measurement system
Percent Gage R&R quantifies how much of the total study variation comes from the measurement system versus actual part-to-part variation.
Question 6: Which statistical measure best describes the central tendency of a data set that contains significant outliers?
- Mean
- Median (Correct answer)
- Mode
- Range
Correct answer: Median
The median is resistant to outliers because it reflects the middle value regardless of extreme high or low values, unlike the mean.
Question 7: In a cause-and-effect (fishbone) diagram, the 'bones' typically represent categories such as:
- Defect counts, opportunity rates, sigma levels, and Cpk values
- Man, Machine, Method, Material, Measurement, and Environment (Correct answer)
- Define, Measure, Analyze, Improve, and Control phases
- Suppliers, Inputs, Process, Outputs, and Customers
Correct answer: Man, Machine, Method, Material, Measurement, and Environment
The classic 6M categories on a fishbone diagram organize potential root causes into Man, Machine, Method, Material, Measurement, and Environment.
Lean Six Sigma Yellow Belt Certification Measure Phase Tools 4
When a process has a Cpk value significantly lower than its Cp value, this indicates that the process: