PECB Six Sigma Yellow Belt key terms

A disciplined, data-driven approach that reduces process variation and defects to improve customer satisfaction and business results, typically targeting fewer than 3.4 defects per million opportunities.

A management philosophy focused on identifying value from the customer's perspective and removing waste from processes so that work flows smoothly at the pace of demand.

An integrated improvement approach that combines Lean's focus on speed and waste elimination with Six Sigma's statistical tools for reducing variation and defects.

A five-phase improvement cycle (Define, Measure, Analyze, Improve, Control) used to solve existing process problems in a structured, data-based sequence.

The first DMAIC stage, where the problem, goal, scope, customer requirements, and team are clarified and formally documented in a project charter.

The DMAIC stage in which the current process performance is quantified through valid data collection, baseline metrics, and measurement system analysis.

The DMAIC stage where data are examined to identify root causes of variation and defects, distinguishing true causes from symptoms and coincidence.

The DMAIC stage in which potential solutions are generated, tested, and implemented to address verified root causes and close the performance gap.

The final DMAIC stage that standardizes the improved process, monitors performance with control charts, and defines a response when metrics drift.

A five-phase design cycle (Define, Measure, Analyze, Design, Verify) used to create a new process or product that meets customer requirements from the start.

Any output or process step that fails to meet a specified customer requirement or internal standard, requiring rework, scrap, or customer compensation.

A normalized metric that counts defects divided by total defect opportunities, multiplied by one million, allowing comparison of processes of different complexity.

A measure of process capability expressing how many standard deviations fit between the process mean and the nearest specification limit, often converted from DPMO.

A measurable characteristic of a product or service that directly reflects what customers value and must be met for them to consider the output acceptable.

The collection of stated and unstated needs, expectations, and feedback gathered from customers and translated into measurable requirements for process improvement.

A diagram that breaks a broad customer need into specific, measurable requirements and then into concrete process specifications that can be monitored.

Any activity that consumes resources without adding value for the customer, commonly classified into categories such as overproduction, waiting, transport, overprocessing, inventory, motion, and defects.

A step that transforms the product or service in a way the customer is willing to pay for, is done correctly the first time, and cannot be omitted.

A step that consumes time or resources without increasing what the customer values; some are necessary under current conditions and are called necessary non-value-added.

The complete sequence of activities, information flows, and people required to move a product or service from request to delivery to the customer.

A visual diagram showing process steps, information flow, inventory, and timing across a value stream, used to identify waste and improvement priorities.

A high-level process map listing Suppliers, Inputs, Process steps, Outputs, and Customers, used early in a project to define scope and boundaries.

A diagram that shows the sequence of steps, decisions, and handoffs in a process, helping teams see complexity, rework loops, and ownership gaps.

A process map organized into horizontal or vertical lanes by role or department, making handoffs, delays, and accountability visible across functions.

The transfer of work, information, or a product from one person, team, or system to another, often a source of delay, error, and lost context.

A cause-and-effect diagram that organizes possible causes of a problem into branches, commonly people, methods, machines, materials, measurement, and environment.

A simple technique of repeatedly asking why a problem occurs, typically five times, to move from symptoms toward an underlying root cause.

The underlying reason a problem occurs which, if removed or corrected, prevents recurrence rather than merely treating the visible symptom.

A bar chart ordered by frequency or impact with a cumulative line, used to focus improvement effort on the few causes producing most of the problem.

The observation that a small proportion of causes, often around 20 percent, typically produces a large proportion of effects, around 80 percent.

The natural differences among outputs, measurements, or process results over time; reducing unwanted variation is a central aim of Six Sigma.

Routine, inherent variability produced by the design of the process itself, requiring management action on the system rather than on individual events.

Unusual variability arising from identifiable, non-routine events or assignable causes that lie outside the normal behavior of the process.

A time-ordered graph of a process metric with a center line and statistically derived limits, used to separate common from special cause variation.

A statistical assessment of whether a stable process can consistently meet specification limits, expressed through indices such as Cp and Cpk.

The upper or lower boundary of acceptable performance defined by customer requirements or design, not by the process's own observed variation.

A study of the equipment, procedures, and appraisers used to collect data, verifying that measurement variation is small enough to trust decisions.

The documented current performance level of a process, measured before improvement, used to quantify the gap and later prove the gain.

A formal document authorizing an improvement project that states the problem, goal, scope, business case, team, milestones, and expected benefits.

The time required to complete one unit of work from start to finish of a process step, or the interval between successive completed units.

The total elapsed time from when a customer requests a product or service until it is delivered, including waiting and queue time.

The available production or service time divided by customer demand, setting the pace at which work must be completed to meet demand.

A relationship stating that average work in process equals average arrival rate multiplied by average time in the system, useful for predicting queues.

The amount of work or material that has entered a process but is not yet finished, tying up capacity and lengthening lead times.

A flow design in which downstream demand triggers upstream work, limiting inventory and preventing overproduction compared with push scheduling.

A visual signal, often a card or electronic marker, that authorizes replenishment or the next step of work in a pull-based process.

A documented, agreed sequence of steps, times, and quality checks that represents the current best method and becomes the baseline for further improvement.

A philosophy and practice of continuous, incremental improvement carried out by the people who do the work, often through small rapid changes.

A four-step improvement cycle (Plan, Do, Check, Act) used to test changes on a small scale, learn from results, and standardize what works.

A limited trial of a proposed change in a controlled setting to verify its effect and surface risks before full-scale implementation.

An action taken to eliminate or reduce a verified root cause, chosen for its likely effect and feasibility rather than as a quick fix.

The total cost incurred from defects and lost performance, including appraisal, internal failure, external failure, and prevention-related expenditures.

The proportion of units or steps that meet requirements without rework or scrap, often calculated at a process step or across the whole process.

The probability that a unit passes through every process step without a defect, calculated by multiplying the first-pass yields of individual steps.

A statistic measuring the typical spread of data around the mean, used to quantify variation and to calculate capability and sigma level.

A framework classifying customer needs as basic, performance, or delighting, showing that different requirement types affect satisfaction in different ways.

An approach applying Six Sigma principles and statistical tools to the design of new products and processes so capability is built in rather than improved later.

A statistical procedure that evaluates whether observed differences in data are likely real or explainable by chance, supporting cause-and-effect conclusions.