Practice questions · Project Management
Lean Six Sigma Green Belt (IASSC ICGB): Practice Questions
Original concept-check questions for the IASSC Lean Six Sigma Green Belt (ICGB), following the DMAIC phases (Define, Measure, Analyze, Improve, Control). Every answer is explained, including why the others are wrong. The Green Belt scope goes up to correlation and regression but does not include design of experiments. Filter by phase or difficulty. These are original study questions, not real exam questions.
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DMAIC stands for:
Correct answer: B. DMAIC stands for Define, Measure, Analyze, Improve, Control - the five-phase improvement cycle. The other strings are invented look-alikes that swap in words like Design, Deliver, Model or Audit, which are not DMAIC phases. -
A project charter is used to:
Correct answer: D. A project charter is a Define-phase document that frames the problem, scope, goals and team. Measuring capability belongs to Measure, a hypothesis test to Analyze, and a control plan to Control - a charter replaces none of them. -
'Voice of the Customer' (VoC) refers to:
Correct answer: A. Voice of the Customer is the customer's stated needs and expectations, which drive the project's requirements. It is not the team's own opinion, not the budget, and not a control chart (an SPC monitoring tool). -
A CTQ (Critical to Quality) is:
Correct answer: C. A CTQ translates a customer need into a specific, measurable requirement. It is not a staffing plan or budget code (project-management items), and not a control chart (an SPC tool). -
A SIPOC diagram maps:
Correct answer: D. SIPOC maps Suppliers, Inputs, Process, Outputs and Customers to scope a process at a high level. It is not control limits or sampling intervals (Measure/Control statistics) and is unrelated to project ownership. -
Defining project scope carefully in Define matters because:
Correct answer: B. Tight scope keeps a project achievable and measurable; an unbounded project drifts and cannot be assessed. Scope does not replace measurement, does not guarantee a pass, and clearly does affect success. -
The Measure phase mainly aims to:
Correct answer: A. Measure establishes a data baseline of how the process performs today. Picking a solution happens in Improve, writing the charter in Define, and sustaining gains in Control. -
Continuous data differs from discrete data because it:
Correct answer: C. Continuous data can take any value on a scale (time, weight, temperature); discrete data is counts or categories. It is not 'always larger', and it certainly can be measured - that is what makes it continuous. -
Measurement System Analysis (MSA) checks that:
Correct answer: D. Measurement System Analysis confirms the measurement process itself is accurate and repeatable before you trust the data. It does not check the budget, customer satisfaction, or the control plan (a Control-phase document). -
Process capability indices (Cp, Cpk) compare:
Correct answer: B. Capability indices (Cp, Cpk) compare the spread of a process against its specification limits, showing whether it can meet requirements. They do not compare people, budgets or suppliers. -
DPMO measures:
Correct answer: A. DPMO stands for Defects Per Million Opportunities, a standardised defect rate that lets different processes be compared. The other expansions (Dollars Per Month Output, Data Points Measured Once, Defects Proven Manually Once) are invented, not Six Sigma terms. -
A baseline measurement is important because:
Correct answer: B. A baseline records the starting performance so you can later prove the process actually improved. It is not just charter paperwork, sets no 'pass mark', and does not replace Analyze (which finds root causes). -
The Analyze phase focuses on:
Correct answer: C. Analyze uses data to find the root causes of the problem. Selecting the project happens in Define, while writing the control plan and sustaining gains belong to Control. -
A fishbone (Ishikawa) diagram is used to:
Correct answer: D. A fishbone (Ishikawa) diagram organises possible causes of a problem by category to guide root-cause analysis. It does not plot control limits (SPC), schedule work, or measure capability (Cp/Cpk). -
A Pareto chart helps you:
Correct answer: B. A Pareto chart ranks causes by frequency so you target the 'vital few' that drive most of the problem (the 80/20 idea). It is not for tracking remaining work, validating measurement (MSA), or writing the charter. -
A hypothesis test is used to:
Correct answer: C. A hypothesis test judges whether an observed difference is statistically real or just chance variation. Setting control limits is SPC, drawing a process map is a mapping tool, and supplier choice is unrelated. -
Correlation between two variables tells you:
Correct answer: A. Correlation measures how strongly two variables move together, but not causation - a strong correlation does not prove one causes the other. It has nothing to do with the budget or control plan. -
Regression analysis is used to:
Correct answer: D. Regression models the relationship between variables, often to predict an output from one or more inputs. Auditing suppliers, scheduling and charter-writing are project or sourcing activities, not statistical modelling. -
The Improve phase is where the team:
Correct answer: A. Improve develops, pilots and implements solutions that address the root causes found in Analyze. Defining the project is Define, measuring the baseline is Measure, and identifying root causes is Analyze. -
Piloting a solution before full rollout helps to:
Correct answer: D. Piloting tests a solution on a small scale first, reducing the risk of a costly full rollout. It cannot guarantee zero defects, and it does not let you skip measurement or the Control phase - it informs them. -
Poka-yoke (mistake-proofing) means:
Correct answer: B. Poka-yoke designs the process so errors are hard or impossible to make in the first place. It is not about larger batches, more end-inspection, or removing documentation - it prevents the error rather than catching it later. -
FMEA (Failure Mode and Effects Analysis) is used to:
Correct answer: C. FMEA anticipates how a process could fail and prioritises those risks so the worst are mitigated first. It does not define the customer, measure capability (Cp/Cpk), or plot a control chart (SPC). -
When selecting among possible solutions, a Green Belt should prefer the one that:
Correct answer: A. The best solution addresses the verified root cause while fitting real constraints (cost, time, risk). Changing the most at once, ignoring the data, or simply spending the most are poor selection criteria. -
Improvements should be validated by:
Correct answer: B. Improvements are proven by measuring the new results against the baseline captured in Measure. Skipping measurement, assuming success, or relying only on the team's opinion are not evidence. -
The Control phase exists to:
Correct answer: C. Control sustains the gain so the process does not drift back to its old performance. Finding root causes is Analyze, piloting solutions is Improve, and defining the project is Define. -
A control plan documents:
Correct answer: D. A control plan documents how the improved process will be monitored and maintained - what to measure, the limits, and how to respond. It is not the customer's address, a hypothesis-test result, or merely the budget. -
Statistical Process Control (SPC) uses control charts to:
Correct answer: A. Statistical Process Control uses control charts to monitor a process over time and flag unusual (special-cause) variation. Defining the charter and selecting the project are Define activities, and brainstorming causes is a fishbone exercise. -
A point falling outside the control limits on an SPC chart signals:
Correct answer: D. A point outside the control limits signals possible special-cause variation worth investigating - something unusual has happened. It does not mean the process is perfect, over budget, or that the customer is satisfied. -
Standardising the new process (standard work) in Control helps because:
Correct answer: B. Standardising the new process (standard work) makes the improvement the repeatable, documented norm so it sticks. It does not hide changes, remove monitoring, or restart DMAIC - those would undo the gain. -
Kaizen refers to:
Correct answer: C. Kaizen is the philosophy of continuous, incremental improvement by everyone over time. It is not a one-off large project, and it is neither a control chart nor a customer survey (specific tools). -
A project goal statement is most useful when it is:
Correct answer: D. A strong goal is SMART, which makes success unambiguous and trackable. A vague goal cannot be measured, a cost-only goal ignores quality and time, and writing the goal after the project defeats its purpose. -
A high-level process map (such as SIPOC) is created in Define mainly to:
Correct answer: B. A SIPOC scopes the process at a high level so the team agrees its boundaries early. Calculating savings, hypothesis testing and setting control limits happen in later phases. -
A project's 'problem statement' should describe:
Correct answer: C. A problem statement describes the performance gap and its impact while staying solution-neutral. Naming the solution biases the work, supplier names are scope detail, and the control plan is a Control output. -
Translating the Voice of the Customer into measurable requirements produces:
Correct answer: A. CTQs turn customer needs into specific, measurable requirements. A Gantt chart schedules work, a control chart monitors a process, and a fishbone organises possible causes. -
Which is a primary responsibility of the project sponsor (champion)?
Correct answer: D. The sponsor or champion secures resources and clears organisational barriers. Running tests, mapping processes and collecting data are the team's and Green Belt's hands-on work. -
A stakeholder analysis in Define helps the team to:
Correct answer: A. Stakeholder analysis identifies who is affected and how to engage them. Computing capability, replacing the charter and setting control limits are unrelated to it. -
'Critical to Cost' (CTC) and 'Critical to Delivery' (CTD) are examples of:
Correct answer: B. CTC and CTD are members of the Critical-to (CTx) family of measurable requirements derived from customer needs, alongside CTQ. They are not charts, tests or sampling plans. -
The 'project Y' in Define usually refers to:
Correct answer: C. The project Y is the primary output or response the project sets out to improve, with the Xs being the inputs that affect it. It is not the budget, supplier list or team size. -
An operational definition is important because it:
Correct answer: B. An operational definition makes a measure unambiguous so different people collect data consistently. It does not set budgets, replace data collection, or guarantee normality. -
In a Gage R&R study, 'repeatability' refers to variation from:
Correct answer: A. Repeatability is the variation when one person measures the same item repeatedly with the same gauge. Variation between different appraisers is reproducibility, not repeatability; yearly drift and customer opinion are unrelated. -
In a Gage R&R study, 'reproducibility' refers to variation from:
Correct answer: C. Reproducibility is the variation between different appraisers measuring the same item. One person repeating a measurement is repeatability; specification limits and sample size are different concepts. -
A process with a sigma level of 6 corresponds to roughly:
Correct answer: D. A six sigma process corresponds to about 3.4 defects per million opportunities, allowing for the conventional 1.5 sigma long-term shift. It is not 50% defects, one per thousand, or zero variation. -
Cpk differs from Cp because Cpk also accounts for:
Correct answer: A. Cp measures potential capability (spread vs tolerance), while Cpk also reflects how centred the process is relative to the limits. Schedule, appraiser count and cost of poor quality are not part of Cpk. -
A Cp of 1.33 is generally interpreted as a process that is:
Correct answer: B. A Cp of 1.33 indicates the process spread fits comfortably within the specification, a common capability benchmark. Cp alone does not show centring, and capability does not mean a process is free of all defects. -
The mean, median and mode are all measures of:
Correct answer: C. Mean, median and mode describe central tendency (the centre of the data). Spread is captured by range or standard deviation, while correlation and capability are different measures entirely. -
Which pair are both measures of dispersion (spread)?
Correct answer: D. Range and standard deviation both measure spread. Mean and median measure centre, Cp and Cpk measure capability, and supplier/customer are SIPOC elements. -
Attribute (discrete) data is best collected with a:
Correct answer: C. Attribute data (counts and categories) is naturally captured on a check sheet by category. A continuous log suits continuous data, a regression line models relationships, and a control plan is a Control document. -
Before drawing conclusions from process data, a Green Belt should first confirm that:
Correct answer: A. Measurement System Analysis confirms the data can be trusted before any conclusions are drawn. Customer satisfaction, budget approval and a signed control plan do not validate the data. -
A baseline sigma level or DPMO is captured in Measure so that the team can later:
Correct answer: D. A baseline records starting performance so improvement can be demonstrated later. It does not let you skip Analyze, set prices, or choose a sponsor. -
The null hypothesis (H0) in a test typically states that:
Correct answer: B. The null hypothesis states there is no difference or no effect; the test looks for evidence against it. It does not assert a large effect, predict project success, or claim the data are normal. -
A p-value of 0.02 with a significance level of 0.05 means you should:
Correct answer: C. Since 0.02 is below the 0.05 alpha, you reject the null hypothesis and treat the result as statistically significant. You would only fail to reject if the p-value were above alpha; budget and ignoring the result are irrelevant. -
To compare the means of two independent groups of continuous data, a common test is the:
Correct answer: B. A two-sample t-test compares the means of two independent groups of continuous data. A Pareto chart ranks categories, a control chart monitors over time, and a SIPOC scopes a process. -
To test whether two categorical (attribute) variables are associated, you would use a:
Correct answer: A. A chi-square test checks for association between categorical variables. A t-test compares means of continuous data, a capability study compares to specs, and a run chart shows data over time. -
The '5 Whys' technique is used to:
Correct answer: D. The 5 Whys repeatedly asks 'why' to move from a symptom toward a root cause. It does not set control limits, estimate budgets, or schedule work. -
The main categories on a classic manufacturing fishbone diagram are often summarised as the:
Correct answer: C. A manufacturing fishbone often uses the 6 Ms to organise potential causes. The 4 Ps, five forces and 'three sigma rules' are unrelated frameworks. -
A correlation coefficient (r) of +0.85 indicates:
Correct answer: D. An r near +0.85 shows a strong positive linear relationship, where the variables rise together. It is not negative or absent, and correlation alone never proves causation. -
In simple linear regression, R-squared represents:
Correct answer: B. R-squared is the proportion of variation in the output explained by the model. The slope is a separate coefficient, the count of data points is the sample size, and the p-value tests significance. -
Multiple regression (within Green Belt scope) is used to:
Correct answer: A. Multiple regression models an output from several inputs simultaneously and is included in the Green Belt body of knowledge. It is not a designed experiment (DOE, reserved for Black Belt), a control plan, or a SIPOC. -
A scatter plot is most useful for:
Correct answer: D. A scatter plot shows the relationship between two continuous variables, often before fitting a regression. Counting by category suits a Pareto or bar chart, a single value over time suits a run chart, and steps suit a process map. -
At Green Belt level, which technique is explicitly OUT of scope for Analyze and Improve?
Correct answer: B. Design of experiments is reserved for the Black Belt and is not part of the Green Belt scope. Correlation, simple regression and multiple regression are all within Green Belt scope. -
Failing to reject the null hypothesis means:
Correct answer: A. Failing to reject the null means the data do not provide enough evidence for an effect; it does not prove the null true. It says nothing about a large effect, and it does not make the test invalid. -
A solution-selection matrix (for example weighting impact against effort) helps the team to:
Correct answer: C. A selection matrix compares solutions against agreed criteria such as impact, cost and effort. It does not set control limits, run tests, or define customers. -
The '5S' workplace method (Sort, Set in order, Shine, Standardize, Sustain) primarily improves:
Correct answer: D. 5S organises the workplace for efficiency and visual control, reducing waste from searching and disorder. It has nothing to do with regression, p-values, or sample size. -
In Lean, the eight wastes are often remembered by the acronym:
Correct answer: C. DOWNTIME (Defects, Overproduction, Waiting, Non-utilised talent, Transportation, Inventory, Motion, Extra-processing) lists the eight wastes. SIPOC, DMAIC and Cpk are different tools. -
Value-stream mapping is used in Improve to:
Correct answer: A. Value-stream mapping reveals the flow of material and information so the team can target waste and improve flow. It does not validate measurement, set alpha, or choose sponsors. -
A pull system (as in Kanban) aims to:
Correct answer: B. A pull system produces to actual demand, which limits overproduction and inventory. It does not maximise inventory, remove measurement, or increase batches. -
A pilot (small-scale trial) before full rollout is valuable because it:
Correct answer: C. A pilot tests a change on a small scale first, limiting the cost if it does not work as hoped. It cannot guarantee zero defects, does not replace the control plan, and does not remove the need to measure. -
Poka-yoke (mistake-proofing) is preferred over relying on inspection because it:
Correct answer: D. Poka-yoke designs the step so the error is hard or impossible to make, preventing defects rather than catching them afterwards. It is not about paperwork, batch size, or removing control charts. -
An FMEA's Risk Priority Number (RPN) is calculated by multiplying:
Correct answer: A. RPN is severity multiplied by occurrence multiplied by detection, ranking which failure modes to address first. Cost/time/scope, the averages, and the capability metrics are not used to compute RPN. -
After implementing improvements, the team should confirm the gain by:
Correct answer: B. The gain is confirmed by re-measuring and comparing against the baseline captured in Measure. Assuming success, relying on one opinion, or closing immediately are not evidence of improvement. -
A cost-benefit analysis in Improve helps decide whether a solution is:
Correct answer: C. A cost-benefit analysis weighs a solution's expected benefits against its costs to support the decision to implement. It is not a test of significance, normality, or control. -
The main goal of the Control phase is to:
Correct answer: A. Control sustains the gain so the process holds its new performance. Finding root causes is Analyze, while writing the charter and selecting the project are Define activities. -
On a control chart, the centre line usually represents the:
Correct answer: D. The centre line is the process average of the plotted statistic, with control limits set around it. It is not a specification limit, a price, or the sample size. -
Control limits on an SPC chart are based on:
Correct answer: B. Control limits come from the process's own variation, commonly set at three sigma from the centre line, and are different from specification limits. They are not based on budget or team size. -
A key difference between control limits and specification limits is that:
Correct answer: C. Control limits reflect the voice of the process (actual variation), while specification limits reflect the voice of the customer (requirements). They are not identical; specifications come from requirements, and control limits come from the process. -
Common-cause variation is best described as:
Correct answer: B. Common-cause variation is the natural variation inherent in a stable process. A one-off disruption is special-cause variation; common-cause variation is not necessarily a defect and should be understood, not ignored. -
A run of several consecutive points on one side of the centre line on a control chart may indicate:
Correct answer: D. A long run on one side of the centre line is a non-random signal that may indicate a special cause to investigate. It does not prove capability, customer satisfaction, or a reason to stop monitoring. -
A response plan within a control plan specifies:
Correct answer: A. A response plan defines the action to take when a monitored measure goes out of limits, so problems are corrected quickly. It is not a marketing budget, stakeholder list, or start date. -
Standard work (documented standard operating procedures) supports Control because it:
Correct answer: C. Standard work captures the improved method as the documented, trained norm so the gain sticks. It does not hide the change, remove monitoring, or restart the project. -
Handing the improved process to the process owner at the end of Control ensures that:
Correct answer: A. Handover gives day-to-day ownership and the control plan to those who run the process, sustaining the gain after the project ends. It is not meant to let the improvement lapse, keep the team in control indefinitely, or cancel monitoring. -
Calculating and reporting the realised financial benefit at the end of a project helps to:
Correct answer: B. Reporting realised benefits validates the project's value and informs which projects to pursue next. It does not set control limits, define customers, or run tests. -
Which chart would you typically use to monitor the number of defects per unit over time?
Correct answer: D. Attribute control charts such as c and u charts monitor counts of defects over time. A scatter plot shows relationships, a SIPOC scopes a process, and a fishbone organises causes. -
The PDCA (Plan-Do-Check-Act) cycle relates to Control because it:
Correct answer: C. PDCA is a continuous improvement loop that supports maintaining and refining the process over time. It does not replace DMAIC, belong only to Define, or set budgets. -
Takt time is best defined as:
Correct answer: D. Takt time is available production time divided by customer demand, setting the pace needed to meet demand. It is not an experiment time, a standard deviation, or DPMO. -
Cycle time in a process refers to:
Correct answer: B. Cycle time is the time to complete one unit or cycle of the process. It is not the whole project duration, the control limit width, or a satisfaction score. -
A histogram is mainly used to:
Correct answer: A. A histogram shows the distribution of continuous data, revealing shape, centre and spread. Ranking categories is a Pareto chart, mapping suppliers and customers is SIPOC, and tracking over time is a run chart. -
The 'vital few' idea behind the Pareto principle suggests that:
Correct answer: B. The Pareto principle holds that a small number of causes (the vital few) drive most of the effect, guiding where to focus. Causes do not contribute equally, effects do have causes, and more causes is not a goal. -
A 'rolled throughput yield' (RTY) measures:
Correct answer: A. RTY is the probability that a unit passes every step defect-free, capturing hidden rework across the whole process. It is not a cost, a regression slope, or a stakeholder count. -
Choosing a representative sample matters because:
Correct answer: D. A representative sample lets you draw valid conclusions about the process; a biased sample misleads. Larger samples cost more, sampling does not remove analysis, and it does not guarantee capability. -
A project that aims to reduce variation as well as shift the average is consistent with Six Sigma because:
Correct answer: C. Six Sigma seeks to both centre the process on target and reduce its spread, since both affect defects. Focusing on only the average or only the spread is incomplete, and variation certainly can be reduced.
Practice questions FAQ
- Are these real ICGB exam questions?
- No. These are original study questions written to test understanding. They are not real exam questions, exam dumps, or copied from any provider.
- How should I use these practice questions?
- Answer each one, read the explanation (including why the wrong options are wrong), and use the per-domain score below to focus your revision on weak areas. Revisit before exam day.
- How many questions should I do before the exam?
- Enough to score consistently across every domain, alongside full-length practice from official or reputable providers. Understanding why each answer is right matters more than raw volume.
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- A good signal is consistently scoring around 80% or higher across all domains on questions you have not seen before, and being able to explain why the wrong options are wrong.
- Should I use exam dumps?
- No. Dumps (real or leaked questions) breach provider policy, can void your certification, and do not build the understanding the exam actually tests.