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Return to course: Lean Six Sigma – Green Belt Programme
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Course Overview
Final Green Belt Certification Quiz
Which development is most closely associated with the emergence of Six Sigma as a formal quality-improvement approach?
*
Motorola's data-driven defect-reduction initiative
The invention of the Gantt chart
The creation of ISO 9001
The introduction of Kanban in Japan
What is the primary purpose of the DMAIC framework?
*
To provide a structured method for improving an existing process
To replace all routine operational management
To design a completely new product only
To eliminate the need for process measurements
A Six Sigma project should normally begin with which condition?
*
A clearly defined business or customer problem
A preferred solution selected by the team
A completed Control Plan
A finalized regression model
Which characteristic makes a project especially suitable for Green Belt treatment?
*
The problem is measurable and the team can influence the process
The solution is already mandated and no analysis is needed
The problem has no measurable outcome
The project requires enterprise-wide transformation beyond the team's authority
Why is project selection important before detailed analysis begins?
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It helps ensure that improvement effort is directed toward a meaningful, feasible problem
It guarantees that the process will be normally distributed
It eliminates the need for a project charter
It determines the final statistical result in advance
Which statement best describes a problem statement?
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It describes the current undesirable condition without prescribing the solution
It specifies the exact improvement tool to be used
It lists the team's preferred future solution
It states only the project completion date
Which item establishes what the project will and will not address?
*
Scope and out-of-scope boundaries
Histogram bins
P-value
Control limits
Who normally provides organizational sponsorship, removes major barriers and supports the project at a leadership level?
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Project Sponsor
Green Belt
Data collector
Operator
What is the main purpose of a project goal statement?
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To define the intended measurable improvement
To describe every possible cause
To list all statistical tests
To replace the problem statement
A team discovers that its original project scope is expanding to include several unrelated processes. What risk is this?
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Scope creep
Repeatability
Stratification
Centering
Which DMAIC phase establishes the problem, business case, goal and project boundaries?
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Define
Measure
Analyze
Control
Which DMAIC phase focuses on establishing reliable baseline performance?
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Measure
Define
Improve
Control
Which phase primarily identifies and verifies important causes of the problem?
*
Analyze
Define
Improve
Control
Which phase is primarily concerned with developing and implementing solutions?
*
Improve
Measure
Analyze
Define
Which phase ensures the improved process remains stable and performs as intended?
*
Control
Define
Analyze
Improve
Which project should generally be approached cautiously as a Six Sigma improvement project?
*
A problem for which management has already mandated the exact solution
A measurable defect problem with available data
A cycle-time problem within the team's influence
A customer-impact problem with a clear baseline
Which is a useful preliminary charter element because it identifies conditions that may affect project execution?
*
Histogram title only
Assumptions and constraints
Regression intercept
Control chart centerline
Why should stakeholders be identified during charter development?
*
They determine the mathematical formula for sigma level
They eliminate the need for process owners
Their interests and influence can affect project adoption and results
They replace the project team
Which criterion directly addresses whether the project can be supported by credible evidence?
*
Data availability
Font selection
Meeting frequency
Number of slides
A project has high customer impact, measurable performance, available data, manageable scope and sponsor support. What does this combination primarily indicate?
*
Strong project-selection characteristics
Guaranteed statistical significance
Guaranteed capability improvement
A completed root-cause analysis
Which data type represents counts such as the number of defects on a unit?
*
Discrete quantitative data
Continuous quantitative data
Nominal data only
Interval data only
Which measurement is continuous?
*
Number of defects
Component diameter measured in millimetres
Number of complaints
Number of rejected units
Which scale has categories with a meaningful order but without equal numerical intervals?
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Ordinal
Nominal
Interval
Ratio
Which scale has a meaningful zero and permits meaningful ratios?
*
Ratio
Nominal
Ordinal
Interval
Which sampling method gives each member of a population an equal basic chance of selection?
*
Simple random sampling
Convenience sampling
Cluster sampling only
Judgment sampling
A company divides employees into day, evening and night shifts and samples from each shift. Which method is being used?
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Stratified sampling
Convenience sampling
Simple random sampling without strata
Cluster sampling
What is the primary concern with convenience sampling?
*
It always requires too many observations
It cannot contain numerical data
It automatically creates normal data
It may not represent the target population
Which statistic is least affected by a single extreme outlier?
*
Median
Mean
Variance
Standard deviation
For the values 4, 5, 5, 6, 6, 7, 8, 8, 9, 22, what is the median?
*
6.5
7.0
8.0
8.5
Which graph is particularly useful for displaying the relative frequency of categories in descending order and highlighting the vital few?
*
Pareto chart
Histogram
Scatterplot
Box plot
Which graph is most appropriate for showing the distribution of continuous numerical data?
*
Pareto chart
Histogram
Fishbone diagram
RACI matrix
Which measure describes the spread of observations around the mean?
*
Median
Standard deviation
Mode
Percentile rank
A z-score expresses a value's position relative to what?
*
The mean in standard-deviation units
The median in percentage units
The specification limits in defect units
The control limits in count units
Which condition is required for a standard binomial model?
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A fixed number of trials with two outcomes and a constant probability of success
Continuous measurements with no defined trials
Events that must occur at a constant rate per unit interval only
A measurement system with multiple appraisers
What is the role of the null hypothesis?
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It always represents the desired improvement
It represents the baseline claim tested against evidence from the sample
It is automatically proven true
It is the same as the p-value
At α = 0.05, a test produces p = 0.02. What is the statistical decision?
*
Fail to reject H₀
Reject H₀
Accept H₀ as proven
Increase α automatically
What does a p-value represent in hypothesis testing?
*
The probability, under H₀, of observing evidence at least as extreme as that obtained
The probability that H₀ is true
The percentage of defects in the population
The probability that the sample is biased
Which test is appropriate when the response is a single population proportion compared with a specified target proportion?
*
One-sample proportion test
Two-sample mean test
Paired mean test
Regression analysis
Which comparison is appropriate for two independent groups when the response is continuous?
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Two-sample mean test
One-sample proportion test
Attribute agreement analysis
Pareto analysis
When measurements are taken on the same subjects before and after an improvement, which design is especially relevant?
*
Independent two-sample analysis only
Paired analysis
Cluster sampling
Poisson modelling
Why should practical significance be considered in addition to statistical significance?
*
Statistical significance guarantees financial benefit
Practical significance replaces all statistical tests
A statistically detectable difference may be too small to matter operationally
Statistical significance is unrelated to sample size
What does a correlation coefficient near +1 indicate?
*
A strong positive linear association
A strong negative linear association
No relationship of any kind
Proof that X causes Y
In the regression equation Ŷ = b₀ + b₁X, what does b₁ represent?
*
The estimated change in Y for a one-unit increase in X
The predicted value when X is zero only
The correlation coefficient
The residual standard deviation
What does R² describe in a simple linear regression context?
*
The proportion of variation in the response explained by the fitted linear model
The probability that the model is causal
The number of observations
The slope expressed as a percentage
Which statement is correct about correlation and causation?
*
Correlation always proves causation
Correlation alone does not establish causation
Negative correlation proves the absence of causation
A high R² automatically proves causation
Why are residuals examined after fitting a regression model?
*
To assess patterns that may indicate model inadequacy
To calculate the project charter
To classify nominal data
To replace the response variable
A scatterplot shows that defects increase as temperature increases. What should the Green Belt do before declaring temperature the root cause?
*
Investigate the relationship further and consider other possible causes
Immediately change temperature
Treat correlation as proof of causation
Remove observations that do not support the relationship
Which condition most directly determines whether a proportion test or mean test is appropriate?
*
The project title
Whether the response parameter of interest is a proportion or a mean
The number of stakeholders
The Control Plan format
What is the correct interpretation of 'fail to reject H₀'?
*
The evidence is insufficient at the chosen significance level to reject H₀
H₀ has been proven true
The alternative hypothesis has been proven false
The sample contains no variation
What is the primary purpose of Measurement System Analysis?
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To increase specification limits
To determine whether the measurement system is adequate for the intended decision or analysis
To select project sponsors
To calculate takt time
Attribute Agreement Analysis is primarily used when the measurement result is:
*
Categorical, such as Accept/Reject or defect classification
A continuous physical dimension only
A project financial benefit only
A takt-time calculation
Which agreement dimension compares an appraiser's classifications with a known standard, when a standard is available?
*
Appraiser-to-standard agreement
Part-to-part variation
Repeatability only
Process capability
What does Cohen's Kappa primarily measure?
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Continuous process capability
Within-part dimensional variation
Categorical agreement beyond what would be expected by chance
Financial return on investment
Which expression defines Cohen's Kappa?
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(Po + Pe) / (1 + Pe)
(Po − Pe) / (1 − Pe)
Po × Pe
Po − 1
Why can percentage agreement and Kappa tell different stories?
*
Kappa accounts for expected chance agreement whereas simple percentage agreement does not
Percentage agreement uses continuous data only
Kappa ignores categorical classifications
Percentage agreement automatically adjusts for prevalence
Gage R&R is designed primarily for what type of measurement system?
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Variable or continuous measurement systems
Attribute classifications only
Project stakeholder analysis
Sampling plans only
What is repeatability in a Gage R&R study?
*
Variation when the same operator measures the same part repeatedly with the same instrument
Variation between different parts only
Variation between project sponsors
Difference between specification limits
What is reproducibility?
*
Variation associated with differences between operators or appraisers
Variation caused only by different parts
Difference between USL and LSL
Difference between mean and median
Why should process stability generally be established before capability analysis?
*
Capability estimates are more meaningful when the process behavior is reasonably stable
Stability guarantees Cp = 1.33
Capability analysis creates stability
Control charts require specification limits
Which formula represents Cp?
*
(USL + LSL) / (6σ)
(USL − μ) / (3σ)
(USL − LSL) / (6σ)
(μ − LSL) / (3σ)
Which formula represents Cpk?
*
min[(USL − μ)/(3σ), (μ − LSL)/(3σ)]
(USL − LSL)/(3σ)
(USL + LSL)/(6σ)
μ/(3σ)
A process has Cp = 1.33 but Cpk = 0.67. What does this pattern indicate?
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The measurement system has zero variation
The process has potential capability but is poorly centered relative to the specifications
The specifications are absent
The process must be perfectly centered
Which metric uses overall observed variation rather than within-process variation?
*
Pp
Cp
Cpk
Within subgroup range
What does DPMO measure?
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Defects per million opportunities
Defectives per measured operation
Deviations per mean observation
Data points per measurement operator
What is the main purpose of a control chart?
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To distinguish routine process variation from signals requiring investigation
To define customer specifications
To replace all process measurements
To calculate a project charter
What is common-cause variation?
*
A confirmed measurement error only
Variation inherent in the process system under its current conditions
A single operator mistake by definition
A specification limit
What is special-cause variation?
*
Variation attributable to a specific, unusual source that can potentially be identified
Variation that always occurs randomly
The difference between USL and LSL
The process mean
Which chart is commonly appropriate for individual continuous observations when rational subgroups of multiple observations are not available?
*
Xbar-R chart
I-MR chart
np chart
c chart
Which chart is commonly used for the number of defectives in samples of constant size?
*
np chart
p chart
c chart
u chart
Which chart is appropriate for the proportion defective when sample sizes may vary?
*
np chart
p chart
c chart
Xbar chart
Which chart is designed for counts of defects when the area or opportunity for defects is constant?
*
c chart
u chart
p chart
I chart
Why are rational subgroups important?
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They guarantee normality
They help organize observations so within-subgroup variation represents short-term process variation
They eliminate special causes
They replace specification limits
How do control limits differ from specification limits?
*
Control limits describe expected process behavior; specification limits describe customer or engineering requirements
They are always identical
Specification limits are calculated from the control chart
Control limits are set by the customer only
A point falls outside a statistically calculated control limit. What is the appropriate first response?
*
Investigate for a special cause
Automatically change the specification
Delete the observation
Assume the process is permanently incapable
Why should an out-of-control process generally be investigated before capability is interpreted?
*
Special-cause behavior can distort estimates of normal process variation and capability
Capability analysis always removes special causes automatically
Control charts require a high Cpk
Specifications are unnecessary
What is a reaction plan?
*
A predefined response to specified abnormal conditions or control signals
A list of project team names
A customer satisfaction survey
A replacement for standard work
Which item is essential in a Control Plan?
*
Only the project title
Only the original problem statement
Measurement method and sampling frequency
Only the final presentation
What is the main advantage of preventive control compared with relying only on final inspection?
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It helps prevent errors or variation before defects reach the customer
It eliminates the need for process monitoring
It guarantees zero defects
It makes specifications unnecessary
Who should normally own ongoing monitoring after a project is handed over?
*
External auditor only
Process Owner
Green Belt permanently
Customer only
Which statement best distinguishes a symptom from a root cause?
*
A symptom is an observed problem effect; a root cause is an underlying cause supported by evidence
A symptom is always the final cause
A root cause is simply the first answer in a brainstorming session
Symptoms and root causes are identical
What is the main purpose of the 5 Whys technique?
*
To progressively explore why a problem occurred until actionable underlying causes are identified
To force exactly five answers in every situation
To replace data collection
To assign blame
Why should root-cause analysis avoid assigning blame to individuals as the primary explanation?
*
System and process conditions often contribute to failures and can be improved
People can never cause errors
Individual behavior is never relevant
Blame automatically improves capability
What is the primary purpose of FMEA?
*
To systematically identify potential failure modes, effects, causes and controls and prioritize actions
To calculate a project's mean
To replace all control charts
To create a stakeholder list
In FMEA, Severity primarily represents:
*
How often the failure occurs
The seriousness of the effect if the failure occurs
How easily the failure will be detected
The project duration
In traditional FMEA scoring, Occurrence represents:
*
The likelihood or frequency of the failure cause or mode occurring
The seriousness of the effect
The ability to detect the failure
The number of project meetings
In traditional FMEA scoring, Detection represents:
*
The severity of the customer effect
The number of operators
The likelihood that existing controls will fail to detect the failure before impact
The process mean
What is the traditional RPN calculation?
*
Severity + Occurrence + Detection
Severity × Occurrence × Detection
Severity ÷ Occurrence × Detection
Severity − Occurrence − Detection
Which of the following is one of the commonly recognized eight Lean wastes?
*
Waiting
Correlation
Regression
Capability
What is the main purpose of Value Stream Mapping?
*
To visualize material and information flow and identify opportunities to improve overall flow
To calculate a p-value
To replace FMEA
To define measurement-system repeatability
Takt time is calculated as:
*
Available production time divided by customer demand
Customer demand divided by available production time
Cycle time divided by defects
Lead time divided by inventory
Which 5S step focuses on arranging needed items so they are easy to find and use?
*
Set in Order
Sort
Shine
Sustain
Kanban is primarily associated with what type of production control?
*
Pull-based flow using signals to control replenishment or work
Unlimited push production
Final inspection only
Statistical hypothesis testing
What is the primary purpose of a WIP limit in a pull system?
*
To restrict work-in-process and help expose or prevent flow bottlenecks
To increase batch sizes indefinitely
To eliminate customer demand
To replace standard work
Which distinction is correct?
*
Lead time is elapsed time through the process; cycle time is the time to perform a process activity or unit of work
Lead time and cycle time always mean exactly the same thing
Cycle time always includes the entire customer waiting period
Lead time excludes waiting by definition
What is the primary purpose of change management in a Six Sigma project?
*
To help people and the organization adopt and sustain the future-state process
To calculate process capability
To replace data analysis
To remove the Process Owner
In a RACI matrix, which role is ultimately answerable for ensuring completion of a task?
*
Responsible
Accountable
Consulted
Informed
What is process drift?
*
Gradual movement away from intended or established process performance
A measurement-system classification error only
A project charter boundary
A sampling method
Why is standard work important after improvement implementation?
*
It eliminates all variation automatically
It defines the agreed method for consistently performing the improved process
It replaces monitoring
It removes the need for process ownership
Why should financial benefits be verified after implementation?
*
To replace the Control Plan
To confirm that claimed benefits are actually realized
To remove process measures
To restart Define
Which combination best supports long-term sustainment?
*
Control Plan, standard work, monitoring, reaction plan and Process Owner
Project presentation, brainstorming and informal reminders only
Baseline data without ongoing monitoring
Training attendance without process controls