Lean Six Sigma & Continuous Improvement Glossary
Explore Lean Six Sigma and continuous improvement through clear, practical definitions of essential tools, techniques, and concepts. Whether you're new to process improvement or expanding your knowledge, this glossary helps you understand the terminology and explore related topics in the RPM Knowledge Hub.
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A Lean workplace organization method using Sort, Set in Order, Shine, Standardize, and Sustain to create an efficient, safe, and organized workplace. Can be referred to as 6S where safety specifically stated in the description.
A root cause analysis technique that repeatedly asks why a problem occurs to identify underlying causes rather than symptoms.
A
A structured problem-solving approach that uses a single-page format to define problems, analyze causes, develop countermeasures, and track results.
A statistical method used to determine whether differences among the means of three or more groups are statistically significant.
A measurement system analysis method that evaluates the consistency and accuracy of people or systems classifying items into categories.
Attribute Data
Data that classify observations into categories, such as acceptable or unacceptable, rather than measuring a continuous numerical characteristic.
B
Bottleneck
A process step or resource whose limited capacity constrains the overall throughput of a system.
Brainstorming
A group technique for generating a broad range of ideas or possible solutions before evaluating or prioritizing them.
C
Capability (Organizational)
The collective ability of people, processes, and systems to consistently achieve desired outcomes and adapt to changing needs.
A visual tool that organizes possible causes of a problem into categories to support structured root cause analysis.
Cellular Manufacturing / Work Cell Design
A production layout that groups people, equipment, and activities to improve flow and reduce movement, delays, and waste.
Common Cause Variation
The natural variation inherent in a stable process, arising from the combined effects of routine system factors.
Continuous Improvement
The ongoing practice of systematically improving processes, products, services, and outcomes through learning and incremental or breakthrough changes.
Statistical graphs that display process performance over time using control limits to distinguish routine variation from unusual changes.
Process capability measures that compare process performance with specification limits, using within-process variation for Cpk and overall variation for Ppk.
Critical-to-Quality (CTQ) Tree / Flow-Down
A structured method for translating customer needs into measurable requirements and specific process or product characteristics.
Cycle Time
The elapsed time required to complete one unit or cycle of work at a process step.
D
Daily Huddles
Brief, structured team meetings used to review performance, identify problems, coordinate priorities, and support timely action.
Data Collection, Sampling & Sample Size
Methods for gathering representative information and determining how much data is needed to support reliable analysis and decisions.
Descriptive vs. Inferential Statistics
Descriptive statistics summarize observed data, while inferential statistics use samples to draw conclusions about a larger population.
Design for Six Sigma (DFSS)
A structured approach to designing new products, services, or processes to meet customer requirements and achieve reliable performance.
A statistical method for systematically testing multiple factors to identify their individual and combined effects on process outcomes.
A five-phase improvement framework—Define, Measure, Analyze, Improve, and Control—used to solve problems and sustain process improvements.
Related performance measures that express defects per million opportunities and the corresponding level of process quality.
E
Eight categories of non-value-added activity: Defects, Overproduction, Waiting, Non-Utilized Talent, Transportation, Inventory, Motion, and Extra-Processing.
The design of processes or devices to prevent mistakes or make errors immediately detectable.
F
A proactive risk assessment method used to identify potential failures, evaluate their consequences, and prioritize preventive actions.
First Pass Yield (FPY)
The percentage of units or transactions completed correctly the first time without rework, repair, or correction.
A cause-and-effect diagram that organizes possible causes of a problem into categories to support systematic investigation.
Flow (Continuous Flow)
The smooth, continuous movement of work through a process with minimal interruption, delay, or unnecessary activity.
G
A measurement system study that evaluates variation caused by measuring equipment and differences among operators.
A structured visit to where work actually occurs to observe processes, engage employees, and understand opportunities for improvement.
Graphical Analysis
The use of charts and graphs to visualize data, identify patterns, trends, relationships, and variation. Common tools include histograms, box plots, scatter plots, run charts, and Pareto charts.
Group Voting / Multivoting
A structured group decision-making technique used to narrow options and prioritize ideas through multiple rounds of voting.
H
Heijunka (Production Leveling)
A Lean method for smoothing production volume and product mix to reduce unevenness, overburden, and waste.
A strategic planning approach that aligns organizational objectives, improvement priorities, performance measures, and responsibilities.
A statistical method for evaluating evidence from sample data to assess claims about a population or process.
I
Inferential Statistics
Statistical methods that use sample data to estimate population characteristics or test hypotheses while accounting for uncertainty.
Another name for the Fishbone or Cause and Effect Diagram, used to organize potential causes of a problem.
J
Just-in-Time (JIT)
A Lean production principle focused on providing what is needed, when it is needed, and in the required quantity.
K
A philosophy and practice of continuous improvement that encourages people at all levels to make ongoing, meaningful improvements.
Visual signals and replenishment methods that control work based on actual demand rather than forecast-driven production.
A method for classifying customer requirements according to how they influence satisfaction, from basic expectations to unexpected delights.
Quantifiable measures used to monitor and evaluate how effectively an organization, team, or process is achieving its performance objectives.
L
Lead Time
The total elapsed time from a customer's request to delivery, including processing, waiting, and other delays.
A management philosophy focused on maximizing customer value while systematically eliminating waste and improving the flow of work.
Little's Law
A relationship stating that average work in process equals average throughput rate multiplied by average time in the system, under stable conditions.
Load Leveling / Work Balancing
The distribution of work across people or process steps to reduce uneven workloads, waiting, and bottlenecks.
Logistic Regression
A statistical technique that models the probability of a categorical outcome, commonly a yes-or-no result, using predictor variables.
M
Managing Change (Change Management)
A structured approach to helping people and organizations adopt, implement, and sustain changes in processes, behaviours, or systems.
A collection of methods used to assess whether a measurement system produces sufficiently accurate, consistent, and reliable data.
Muda, Mura, and Muri
Three Lean concepts describing waste (muda), unevenness (mura), and overburden (muri) that contribute to inefficient or unstable processes.
N
A customer loyalty metric based on how likely customers are to recommend an organization, product, or service.
Normal Distribution
A symmetrical, bell-shaped probability distribution in which values cluster around the mean, with progressively fewer observations occurring farther from the centre.
Normality Testing
Statistical methods used to assess whether a dataset is reasonably consistent with a normal distribution, helping determine the suitability of certain statistical analyses.
Non-Value-Added Activity
Work that consumes resources without directly increasing customer value, although some activities may be necessary for regulatory or operational reasons.
O
Objectives and Key Results (OKRs)
A goal-setting framework that defines ambitious objectives and measurable key results to align priorities, focus efforts, and track progress toward desired outcomes.
A manufacturing performance measure combining Availability, Performance, and Quality to assess how effectively equipment is utilized.
P
Parametric vs. Nonparametric Tests
Two families of statistical methods that differ in their assumptions about data distributions, parameters, and measurement characteristics.
A prioritization technique that ranks categories by frequency, cost, or impact to identify the most significant contributors to a problem.
An iterative improvement method using Plan, Do, Check or Study, and Act to test changes and learn from results.
A Lean technique that prevents errors or makes them immediately visible before they result in defects.
A structured description of a problem using What, Why, Where, When, Who, How, and How Much to clarify its scope and impact.
A statistical assessment of how consistently a stable process can produce results within specified requirements.
A visual representation of process steps, decisions, and handoffs used to understand how work is performed and identify improvement opportunities.
Project Charter
A document that defines an improvement project's problem, objectives, scope, expected benefits, roles, and responsibilities.
Project Planning
The process of defining project activities, resources, responsibilities, timelines, risks, and milestones needed to achieve desired outcomes.
Pull System
A production or service delivery approach in which downstream demand triggers upstream work, helping limit excess inventory and work in process.
Q
Quality
The degree to which a product, service, or process consistently meets defined requirements and customer expectations.
R
RACI / RASCI Matrix
A responsibility assignment tool that clarifies who is Responsible, Accountable, Consulted, Informed, and, in RASCI, Supportive of an activity.
A statistical method used to examine relationships between variables and estimate or predict an outcome from one or more predictors.
Reliability Life Data Analysis / Weibull
Statistical methods used to analyze time-to-failure data, estimate reliability, and understand patterns of product or equipment failure.
A systematic approach to identifying and addressing the underlying causes of problems rather than treating their symptoms.
S
A high-level process mapping tool identifying Suppliers, Inputs, Process, Outputs, and Customers to clarify process boundaries and relationships.
A data-driven improvement approach focused on reducing variation, preventing defects, and improving process performance.
A Lean method for reducing equipment setup and changeover time by separating, simplifying, and streamlining activities. May also be referred to as "Rapid Changeover".
Spaghetti Diagram
A visual map tracing the physical movement of people, materials, or information to reveal unnecessary travel and inefficient layouts.
Special Cause Variation
Process variation arising from identifiable, unusual factors that are not part of the system's routine behaviour.
The documented best-known method for performing a task consistently, providing a baseline for training, performance, and improvement.
Statistical Process Control (SPC)
The use of statistical methods, particularly control charts, to monitor process variation and support stable, predictable performance.
Systems Thinking
An approach to understanding how interconnected parts, relationships, and feedback loops influence the behaviour and performance of an entire system.
T
The pace at which work must be completed to meet customer demand, calculated as available production time divided by required output.
Theory of Constraints (TOC)
A management approach that improves system performance by identifying and managing the constraint limiting overall throughput.
A proactive maintenance approach that engages employees in preventing equipment failures, reducing losses, and improving operational reliability.
V
Value-Added Activity
An activity that transforms a product or service in a way the customer values and is willing to pay for.
A Lean technique for visualizing material and information flows to identify waste and design a more efficient future-state process.
​The use of visual signals, standards, and information to make process conditions, expectations, and abnormalities immediately apparent.
A structured approach to capturing and translating customer needs, expectations, and feedback into actionable improvement requirements.
W
Work Balancing / Load Leveling
The allocation of tasks across workers or process steps to improve flow, reduce waiting, and align capacity with demand.
Work in Process (WIP)
Items or tasks that have entered a process but have not yet been completed or delivered.
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