B303 · Lean Six Sigma

Lean Six Sigma Glossary

Every key term of the course, explained in plain language. Jump to a letter or search for a term.

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5
  • 5 Whys -

    A simple, non-statistical method of repeatedly asking "why" to drill from a symptom down to its root cause.

  • 5-Second Rule -

    The standard that anyone walking into the Gemba should be able to tell within five seconds whether the process is normal or abnormal.

  • 5S Method -

    A lean tool for creating an organized, standardized workplace, in five steps: Sort, Set in Order, Shine, Standardize, Sustain.

6
  • 6 Ms -

    The standard Fishbone categories: Methods, Machines/Equipment, Materials, Manpower/People, Measurement, and Mother Earth/Environment.

7
  • 7 Wastes (Muda) -

    The seven classic categories of non-value-added activity: Transportation, Inventory, Motion, Waiting, Overproduction, Over-Processing, and Defects (TIMWOOD).

a
  • Accuracy -

    The difference between the observed average value of a measurement and the true value of the thing being measured.

  • Affinity Diagram -

    A tool that organizes a large number of ideas or facts into related groups based on natural connections.

  • After Action Review -

    An After Action Review (AAR) is a structured team reflection at the end of a project or task: what was planned, what actually happened, why, and what to carry forward next time.

  • Alternative Hypothesis (H1) -

    The claim that a suspected cause does have a significant effect on the problem.

  • Anti-Solution (Reverse Brainstorming) -

    A technique that asks how to make the problem worse, then reverses the answers to find robust solutions.

  • Attribute Agreement Analysis -

    The MSA tool for discrete or categorical data, measuring how consistently appraisers agree with each other and with a known master value.

  • Autonomous Maintenance (Jishu Hozen) -

    Training operators to perform daily cleaning, lubrication, and basic inspections themselves.

b
  • Baseline -

    The established, quantified level of current process performance for a specific metric (the Y) before any improvement efforts are implemented. It is the definitive benchmark against which all future results will be compared, ensuring the project's success and Return on Investment (ROI) are measured accurately. The Baseline typically includes the average performance, the Standard Deviation (Variation), and the initial Process Sigma Level.

  • Belt System -

    The hierarchy of Lean Six Sigma expertise levels, inspired by martial arts: White Belt, Yellow Belt, Green Belt, Black Belt and Master Black Belt. Each level brings more responsibility for improvement projects.

  • Benchmarking -

    Comparing your organization's processes, products or services with those of other successful organizations, or other departments in your own company, to identify improvement areas and set performance standards.

  • Box Plot -

    A chart displaying the five-number summary of a data set: minimum, Q1, median, Q3, and maximum. Also known as: Box-and-Whisker Plot.

  • Brainwriting (6-3-5 Method) -

    A structured ideation technique where 6 participants each write 3 ideas every 5 minutes, passing their sheet to build on others' ideas.

  • Brown Paper Approach -

    A low-tech, collaborative method of overlaying data (via colored sticky notes) onto a large physical or digital process map.

c
  • Capable Process -

    A process whose Control Limits (VOP) sit comfortably inside its Specification Limits (VOC).

  • Central Limit Theorem (CLT) -

    The principle that the averages of samples will trend toward a Normal Distribution as sample size increases, even if the raw data isn't normally distributed.

  • Change Management -

    The discipline of managing the human side of a process change, to reduce resistance and drive adoption.

  • Common Cause / Special Cause Variation -

    Natural, expected fluctuation (Common Cause) versus unpredictable glitches, errors, or method changes (Special Cause).

  • Confidence Level (CL) -

    Your desired certainty that a sample result reflects the true population value (commonly 95%).

  • Continuous Data -

    Data that can take any value within a range and is measured, not counted (e.g., time, weight, temperature). Also known as: Variable Data.

  • Control Chart (Shewhart Chart) -

    A statistical tool plotting process data over time against a Mean, an Upper Control Limit (UCL), and a Lower Control Limit (LCL), to monitor stability.

  • Control Limits -

    Statistically calculated boundaries on a Control Chart that define the expected range of variation for a stable process. They are based on the process's historical performance (typically set at ±3 standard deviations from the process average) and are used to distinguish between common cause (normal) variation and special cause (unstable) variation.

  • Control Plan -

    A living document defining what's controlled, how it's measured, its boundaries, and the reaction plan if it goes out of control.

  • Correlation -

    A visual or statistical pattern showing that two variables move together.

  • Correlation Coefficient (r) -

    A number from −1 to +1 measuring the strength and direction of a linear relationship between two variables.

  • Cost of Conformance -

    Spending to prevent and catch defects before they happen: prevention costs and appraisal (inspection) costs.

  • Cost of Non-Conformance -

    Costs that result from defects: internal and external failure costs. This is what the Cost of Poor Quality (COPQ) measures.

  • Cost of Poor Quality -

    The Cost of Poor Quality (COPQ) is the cost incurred because a product or service was not made right the first time: the price of defects, mistakes and inefficiencies. It covers internal and external failure costs.

  • Critical to Quality -

    A measurable characteristic of a product, service, or process that a customer considers most important in defining value and quality. CTQs are the objective, quantifiable translation of subjective customer needs (VOC) into actionable metrics, often developed using a VOC Translation Matrix or a CTQ-Tree.

  • Critical Xs -

    The small number of inputs that have the biggest impact on your output (Y). Also known as: Vital Few.

  • CTQ-Tree -

    A visual tool that breaks a high-level customer Need down into measurable Requirements (CTQs) and specific Specifications with targets, limits and units.

  • Current State Map -

    A visual representation of how a process actually works today, as opposed to how it's assumed to work (the SOP). Also known as: As-Is.

  • Customer Requirement -

    A Customer Requirement (CR) is a clean, internal restatement of a Voice of the Customer statement: emotion removed and generalized into a clear customer need.

d
  • Data Collection Plan -

    The blueprint that defines exactly what to measure, how, and by whom, for both your Y and your Critical Xs.

  • Defectives -

    A unit of product or service that contains one or more defects and is therefore unsuitable for its intended purpose. Defectives are typically measured using the Parts Per Million (PPM) metric. Unlike a defect, a unit is either defective (if it has ≥ 1 defect) or not defective.

  • Defects -

    An error, flaw, or non-conformance in a product or service that fails to meet a specific Critical-to-Quality (CTQ) requirement or Specification Limit. A single unit or service can contain multiple defects. In Six Sigma, the goal is to define, measure, and eliminate these occurrences.

  • Defects Per Unit (DPU) -

    The average number of defects found on a single unit: total defects divided by total units inspected.

  • Design for Six Sigma -

    Design for Six Sigma (DFSS) is a systematic methodology for designing new products, services or processes from the ground up, or for fundamentally redesigning existing ones when incremental improvement (DMAIC) won't suffice. Its goal is to build quality in from the start.

  • Design of Experiments (DoE) -

    A statistical method that tests multiple variables (Xs) simultaneously to find the optimal settings for a process.

  • Detailed Flowchart -

    A granular map of a narrow process segment, using standard symbols (Oval, Rectangle, Diamond). Also known as: Process Map.

  • Discrete Data -

    Data that can only take countable values or fall into categories (e.g., pass/fail, defect count). Also known as: Attribute Data.

  • Divergence -

    Gathering as many possible causes as you can before using data to filter and prove the true ones, in contrast to the convergence that follows later in Analyze.

  • DMADV -

    The roadmap most commonly used for Design for Six Sigma (DFSS): Define, Measure, Analyze, Design, Verify.

  • DMAIC -

    The structured problem-solving model behind Six Sigma: Define, Measure, Analyze, Improve, Control. DMAIC is used to improve processes that already exist.

  • DPMO -

    Defects Per Million Opportunities: the number of defects in a process per one million chances for a defect to occur. It is the statistical measure behind the Six Sigma name (3.4 DPMO).

e
  • Entropy -

    In physics (the Second Law of Thermodynamics), entropy states that in an isolated system, disorder always increases over time. Energy spreads out, and things move from a state of organization to a state of chaos unless energy is added to keep them organized.

  • External Failure Costs -

    External Failure Costs (EFC) are costs of defects found after the customer receives the product or service, such as warranty claims, complaints, returns and lost sales.

f
  • Failure Mode and Effects Analysis (FMEA) -

    A formal risk tool that ranks potential failure modes by Severity, Occurrence, and Detection to calculate a Risk Priority Number (RPN).

  • Financial Flow -

    The money that results from the work: invoicing, payments and cash. Faster, more reliable material and information flows are how you improve the health of the financial flow.

  • Fishbone Diagram -

    A visual tool that organizes potential causes into standard categories (the Ms) branching off a spine toward the primary problem.

g
  • Gauge R&R Study -

    The standard MSA tool for continuous data, quantifying repeatability and reproducibility as a percentage of total variation.

  • Gemba -

    Japanese for "the actual place"; going to directly observe a process rather than relying on documents or memory.

  • Golden Keys -

    The top three critical pieces of knowledge a Process Owner needs to run the new process independently.

  • Green Belt -

    A Lean Six Sigma practitioner trained and certified to lead improvement projects.

  • Growth Mindset -

    The belief, described by psychologist Carol Dweck, that abilities can be developed through dedication and hard work — captured in the idea of "not yet" rather than "can't."

h
  • Handoff -

    The point where work — material or information — moves from one lane to another.

  • Hard Savings -

    Tangible, measurable savings that directly and immediately impact the Profit & Loss (P&L) statement, such as less rework, less scrap or lower material costs.

  • Histogram -

    A specialized bar chart showing the distribution, shape, center, and spread of continuous data using bins.

  • House of Quality -

    The central matrix of Quality Function Deployment (QFD). It links what the customer wants (CTQs) to how the organization will deliver it (technical requirements), and adds competitive benchmarking, trade-offs and technical priorities.

i
  • Improvement Plan -

    The finalized, prioritized set of solutions ready to be validated and implemented.

  • In/Out-Frame Method -

    A scoping method that defines project boundaries by explicitly listing what is included (In-Frame) and what is excluded (Out-of-Frame).

  • Information Flow -

    The data and decisions that guide the work: orders, specifications, schedules and approvals. When the information flow breaks, the material flow usually breaks too.

  • Input / Output -

    Input is what goes into a process, such as materials, data or requests. Output is what the process delivers to a customer, internal or external. A process is a structured series of steps that turns inputs into outputs the customer values.

  • Internal Failure Costs -

    Internal Failure Costs (IFC) are costs of defects caught internally, before the product or service reaches the customer, such as scrap, rework or re-inspection.

  • Interrelationship Diagraph (ID) -

    A diagram mapping causal relationships between many interdependent Xs, used to find the highest-leverage "driver causes."

  • Is/Is-Not Method -

    A technique that defines the exact boundaries of a problem by asking what, where, when, how much and who, and answering each question with what the problem is and what it is not.

j
  • Jidoka (Autonomation) -

    The ability of a process to detect a problem and stop itself, so defective parts never flow downstream.

  • Just-in-Time -

    Just-in-Time (JIT) means producing only what is needed, when it is needed, and in the amount needed. It eliminates excess inventory and waiting time.

k
  • Kaizen -

    A philosophy of continuous, incremental improvement involving all employees.

  • Kaizen Blitz -

    A short, high-intensity event (typically 3 to 5 days) focused on rapidly improving a small, defined process area.

  • Kamishibai -

    A visual daily audit system using cards (Green/Red) tied to a board, turning auditing into a predictable, supportive routine.

  • Kanban -

    Japanese for "signboard"; a visual signal that tells an upstream process exactly what to produce or move next.

  • Kano Model -

    A framework by Noriaki Kano that classifies customer requirements into Basic, Performance and Excitement categories, based on how their fulfillment affects customer satisfaction.

  • Key Performance Indicator -

    A Key Performance Indicator (KPI) is a metric an organization monitors to track process performance, such as cycle time, defect rate or customer satisfaction. A KPI that keeps missing its target is a clear signal for improvement.

l
  • Lean -

    Lean (or Lean Thinking) is an approach to achieving speed and efficiency by identifying and removing waste. The term was coined in the late 1980s by James Womack and Daniel Jones, based on their study of the Toyota Production System.

  • Lean Six Sigma -

    A data-driven approach to improving processes by removing waste and reducing variation. Lean Six Sigma (LSS) combines the waste-focused thinking of Lean with the statistical, variation-focused methods of Six Sigma.

  • Linear Regression -

    A statistical method fitting a straight-line equation to two variables, allowing you to predict Y from a given X.

  • Linearity -

    The difference in bias across the entire operating range of a measurement tool.

  • Long List -

    The comprehensive, unfiltered list of potential solutions generated for each root cause, before any evaluation.

m
  • Margin of Error -

    Your desired precision — the maximum acceptable distance between your sample result and the true population value.

  • Material Flow -

    The physical movement of raw materials, products and inventory through an organization. A systems view helps you spot where materials get stuck (bottlenecks) or are moved around unnecessarily.

  • Mean (µ) -

    The arithmetic average of a data set; the center of the distribution.

  • Measurement System Analysis -

    Measurement System Analysis (MSA) is a check that confirms a measurement system is accurate and reliable before you trust the data it produces. It looks at the instrument, the method and the people who measure.

  • Milestone -

    A specific point in time that marks a major event or turning point in a project. A milestone is an achievement, not a task, and has zero duration.

  • Muda -

    The Japanese Lean term for waste: anything that consumes resources without adding value for the customer.

  • Multi-Moment Analysis (Work Sampling) -

    A statistical technique that estimates how time is spent by taking many random, instantaneous observations.

  • Multi-Vari Chart / Simple Comparative Test -

    Simplified alternatives to DoE, used when variables are qualitative rather than purely numerical, as is common in logistics and service.

n
  • New Product Introduction -

    New Product Introduction (NPI) is the process of bringing a new product or service to market, from idea and design to launch.

  • New Standard -

    The finalized way of working after rollout — documented, trained, and physically reinforced, so the improvement becomes routine.

  • Non-Parametric Test -

    A statistical test used instead of a t-Test or ANOVA when your data isn't normally distributed.

  • Non-Value-Added Time (NVA) -

    Time spent on waste: waiting, storage, movement, rework, or inspection.

  • Normal Distribution -

    The symmetrical distribution that predictable processes tend to follow, described by its Mean and Standard Deviation. Also known as: Bell Curve.

  • Normality Test -

    A required pre-check before using t-Tests or ANOVA, confirming whether your data follows a Normal Distribution.

  • Null Hypothesis (H0) -

    The assumption that a suspected cause has no real effect on the problem; the statistical "status quo," innocent until proven guilty.

o
  • One-Piece Flow -

    Moving a single unit at a time through a process, instead of batching, so errors are caught immediately.

  • Operational Definition -

    A clear, unambiguous, agreed-upon definition of a metric, precise enough that two different people measuring the same thing get the same number.

  • Operational Excellence -

    Operational Excellence (OpEx) is the state where an organization consistently delivers maximum value to the customer at the lowest possible cost, every single time.

  • Out of Control Action Plan (OCAP) -

    The defined reaction when a Control Chart signals Special Cause Variation: who is notified, and what immediate steps are taken.

  • Overall Equipment Effectiveness (OEE) -

    A metric measuring equipment performance against its full potential: Availability × Performance × Quality.

p
  • P-Value -

    The probability used to decide between the two hypotheses; a value below 0.05 means the evidence against the null hypothesis is strong enough to reject it.

  • Pareto Chart -

    A bar chart that ranks categories by frequency with a cumulative line, used to identify the "vital few" causes behind most of a problem (the 80/20 principle).

  • Parking Lot -

    A dedicated space where solution ideas are captured and set aside for formal review in Improve, without acting on them prematurely.

  • Parts Per Million -

    A measure of quality that expresses the number of defective units (units with one or more defects) out of every one million units produced. It is a simplified way to compare quality performance across different volumes and industries.

  • Pick Chart (Benefit vs. Effort Matrix) -

    A four-quadrant grid plotting ideas by effort and impact, sorting them into Quick Wins, Major Projects, Fill-ins, and Thankless Tasks.

  • Pilot -

    A limited, controlled launch of a solution in a small part of the process, to validate real-world performance before full rollout.

  • Pilot Observation Log -

    A structured log capturing the qualitative, "why" behind what the pilot's numbers show.

  • Poka-Yoke -

    Japanese for "mistake-proofing"; designing a process so an error is either impossible to make or immediately obvious.

  • Population -

    The entire group you're interested in drawing conclusions about.

  • Power/Interest Grid -

    A Power/Interest Grid (stakeholder matrix) prioritizes stakeholder engagement by plotting each stakeholder's power or influence over the project against their interest in it.

  • Pre-Pilot FMEA -

    An FMEA applied to a new solution before piloting it, to anticipate new failure modes it might introduce.

  • Precision -

    How much variation exists when the same item is measured multiple times.

  • Problem Space -

    The mindset of Define, Measure, and Analyze: observing, measuring, and diagnosing the problem without yet designing a fix.

  • Process Capability Indices -

    Statistical indices comparing process spread (Cp) and process centering (Cpk) against specification limits. Also known as: Cp and Cpk.

  • Process Cycle Efficiency (PCE) -

    The ratio of Value-Added Time to Total Lead Time, expressed as a percentage.

  • Process Encyclopedia -

    A single, accessible location consolidating the final SOPs, Control Charts, and TPM checklists.

  • Process Management -

    The discipline of defining, mapping, executing, monitoring, and continuously improving how work gets done. Process Management is the engine that drives Operational Excellence.

  • Process Owner -

    The person accountable for a process, who sustains the improvement long-term after the project ends.

  • Project Charter -

    The official document that authorizes a project. It defines the problem, goal, scope, team and milestones, and is approved by the sponsor.

  • Project Order -

    The project's team, goals, and scope as defined in the charter — revisited and finalized here in light of proven root causes.

  • Pugh Matrix (Solution Selection Matrix) -

    A weighted-criteria scoring tool used to objectively compare multiple solution candidates.

q
  • Quality Function Deployment -

    Quality Function Deployment (QFD) is a structured methodology that carries customer requirements through every stage of product development, from design engineering to manufacturing and quality control.

  • Quick Win -

    A simple, low-cost improvement identified during Walk the Walls that can be implemented immediately, without complex analysis or significant investment.

r
  • Repeatability -

    The variation that occurs when one person measures the same item multiple times using the same equipment. Also known as: Equipment Variation, EV.

  • Reproducibility -

    The variation that occurs when different people measure the same item using the same equipment. Also known as: Appraiser Variation, AV.

  • Return on Investment -

    Return on Investment (ROI) is the financial benefit of a project relative to its cost.

  • Roll-Back Plan -

    A contingency plan to immediately revert to the old process if a pilot reveals unacceptable risk.

  • Rolled Throughput Yield (RTY) -

    The cumulative probability that a unit passes through every step of a multi-step process defect-free.

  • Root Cause -

    The fundamental, underlying reason a problem occurs, as distinct from its symptoms. If you remove the root cause, the problem does not come back.

  • RPM Method -

    A goal-setting framework developed by Tony Robbins, built on three core questions: your Result, your Purpose, and your Massive Action Plan.

s
  • Sample -

    A subset of the population that you actually collect and analyze, ideally representative of the whole.

  • SCAMPER -

    A 7-lens creativity checklist: Substitute, Combine, Adapt, Modify, Put to another use, Eliminate, Reverse.

  • Scatter Plot -

    A chart plotting a potential cause (X) against the problem (Y) to visually check for correlation.

  • Scope Creep -

    The gradual, uncontrolled expansion of a project's boundaries beyond what was originally agreed. Scope creep costs time and focus; a clear scope in the Define phase helps prevent it.

  • Sigma Level -

    The definitive measure of process capability, expressing how many standard deviations fit between the process performance and the customer's specification limit. Also known as: Z-Score.

  • Silo -

    A department or function that operates in isolation and optimizes its own performance without regard to the wider process. Silo thinking often moves problems from one department to the next instead of solving them.

  • SIPOC -

    An acronym for Suppliers, Inputs, Process, Outputs, Customers. SIPOC is a high-level visual tool for understanding and scoping a process.

  • Six Sigma -

    A disciplined, data-driven approach to reducing variation and eliminating defects. The name refers to a quality level of only 3.4 defects per million opportunities (DPMO). Six Sigma originated at Motorola in the mid-1980s.

  • SMART -

    A standard for writing project goals. A SMART goal is Specific, Measurable, Achievable, Relevant and Time-bound, so everyone knows exactly what success looks like and by when.

  • SMED (Single Minute Exchange of Die) -

    A method for reducing changeover time between products or activities, ideally to under 10 minutes.

  • Soft Savings -

    Real, measurable benefits that do not directly or immediately impact the P&L statement, or that relate to cost avoidance rather than cost reduction, such as productivity gains or higher satisfaction.

  • Solution Space -

    The mindset of Improve: actively redesigning the process to address the proven root causes.

  • Solutionizing -

    The tendency to jump straight to a fix ("I know how to solve this!") before the root cause has been verified with data.

  • Spaghetti Diagram -

    A visual tool tracing the path of a product, document, or person through a process, to identify excessive travel.

  • Specification Limits -

    The boundaries set by the Customer (Voice of the Customer or VOC) that define the acceptable range for a product or service characteristic. They typically include a Lower Specification Limit (LSL) and an Upper Specification Limit (USL). Any output outside these limits is considered a defect.

  • Sponsor Alignment Meeting -

    A checkpoint meeting where the team presents its data and proven causes to renegotiate the goal, team, and timeline for the rest of the project.

  • Stability -

    The total variation of a measurement over a long period of time.

  • Stabilization -

    Removing unpredictable chaos from a process so it behaves consistently over time, before attempting to improve it.

  • Stakeholder -

    Any individual, group or organization that can affect or be affected by a project's activities or outcomes.

  • Stakeholder Management -

    The process of identifying, analyzing, planning and implementing actions to engage stakeholders effectively, so that a project gains support and its results last.

  • Standard Deviation (σ) -

    The average distance of each data point from the mean; the foundation of Six Sigma's process capability measurement.

  • Standard Operating Procedure (SOP) -

    Documentation of the best currently known way to perform a task, used to reduce human variation.

  • Start, Stop, Continue -

    A simple retrospective matrix capturing what a team should start doing, stop doing, and keep doing on future projects.

  • Statistical Process Control -

    Statistical Process Control (SPC) uses control charts and statistical methods to monitor a process over time and detect deviations from the expected standard early, before they turn into defects.

  • Statistically Significant -

    A result unlikely to be due to random chance (typically p < 0.05), confirming a real cause-and-effect relationship.

  • Subject Matter Expert (SME) -

    A person with deep, hands-on knowledge of a process, often a frontline employee.

  • Swimlane Diagram -

    A process map organized into lanes by role, department, or system, highlighting handoffs between them. Also known as: Cross-Functional Map.

  • Systems Thinking -

    Seeing an organization as one connected network, where every part influences every other part, instead of a set of isolated departments. Systems Thinking helps you stop fixing symptoms and find the real, leverage-based root causes of a problem.

t
  • Takt Time -

    The rate at which a product must be completed to meet customer demand: net time available divided by customer demand.

  • Theory of Constraints (TOC) -

    The principle that a process's output is limited by its single biggest bottleneck, and improving any other step first won't increase overall throughput.

  • Time Series Plot -

    A chart plotting data points sequentially over time, used to detect trends, shifts, or instability. Also known as: Run Chart.

  • Tollgate -

    A formal review point at the end of a DMAIC phase where the team pauses, presents its data and gets sign-off before moving on to the next phase.

  • Total Productive Maintenance (TPM) -

    A proactive, preventative maintenance philosophy aiming for zero breakdowns, zero defects, and zero accidents.

  • Toyota Production System -

    The Toyota Production System (TPS) is the production system developed at Toyota after World War II by Taiichi Ohno and Shigeo Shingo. It is built on eliminating waste and creating smooth process flow, and it is the origin of Lean Thinking.

  • Train the Trainer -

    A model where pilot participants become teachers, using peer-to-peer influence to train the rest of the team.

  • Training Record -

    A clear, documented list of who has been qualified to run the new process.

v
  • Value Stream Map (VSM) -

    An end-to-end map of a process showing both material flow and information flow, used to quantify waste.

  • Value-Added Time (VA) -

    The time the customer is willing to pay for — actively transforming the product or service.

  • Visual Control -

    Any communication device in the work environment that shows, at a glance, how work should be done and whether it's currently in control.

  • Vital Few -

    The small handful of causes (per the Pareto Principle) responsible for most of a problem, as opposed to the "Trivial Many."

  • VOC Translation Matrix -

    A tool that converts subjective customer statements (Voice of the Customer) into a clean Customer Requirement and then into a measurable Critical-to-Quality characteristic (CTQ).

  • Voice of the Customer -

    Voice of the Customer (VOC) describes what the customer actually values, captured through interviews, surveys, complaints or observation and translated into concrete requirements.

  • Voice of the Team (VOT) -

    The practical knowledge of Subject Matter Experts who work the process every day — insights into bottlenecks, workarounds, and hidden waste that data alone might never reveal.

w
  • Walk the Walls -

    A team activity that reviews the merged process map and data from the Measure phase to harvest potential causes at each "hot spot."

  • War Room -

    A dedicated, highly visual space — physical or virtual — that serves as the central hub for the project team, combining data, process maps, and findings in one place.

y
  • Y = f(X) -

    The core Lean Six Sigma equation: your output (Y) is a function of multiple inputs (Xs).

  • Y=f(X) Cascade -

    A structured brainstorming tool that breaks a high-level Y down into progressively specific, measurable Xs.

  • Yamazumi Chart -

    A stacked bar chart showing task times per worker or station, used to balance workload against Takt Time.

  • Yield -

    The process success rate at a single step: the percentage of units that pass inspection without a defect.