Affinity Diagram – A technique for organizing individual pieces of information into groups or broader categories.
ANOVA – Analysis of Variance – A statistical test for
identifying significant differences between process or system
treatments or conditions. It is done by comparing the variances around
the means of the conditions being compared.
Attribute Data – Data which on one of a set of discrete values such as pass or fail, yes or no.
Average – Also called the mean, it is the arithmetic
average of all of the sample values. It is calculated by adding all of
the sample values together and dividing by the number of elements (n)
in the sample.
Bar Chart – A graphical method which depicts how data fall into different categories.
Black Belt – An individual who receives approximately four weeks training in DMAIC, analytical problem solving, and methods. A Black Belt is a full time six sigma team leader solving problems under the direction of a Champion.
Breakthrough Improvement – A rate of improvement at or near 70% over baseline performance of the as-is process characteristic.
Capability - A comparison of the required operation
width of a process or system to its actual performance width. Expressed
as a percentage (yield), a defect rate (dpm, dpmo,), an index (Cp, Cpk,
Pp, Ppk), or as a sigma score (Z).
Cause and Effect Diagram – Fishbone Diagram – A
pictorial diagram in the shape of a fishbone showing all possible
variables that could affect a given process output measure.
Central Tendency - A measure of the point about which
a group of values is clustered; two measures of central tendency are
the mean, and the median.
Champion -A Champion recognizes, defines, assigns and
supports the successful completion of six sigma projects; they are
accountable for the results of the project and the business roadmap to
achieve six sigma within their span of control.
Characteristic – A process input or output which can be measured and monitored.
Common Causes of Variation – Those sources of variability in a process which are truly random, i.e., inherent in the process itself.
Complexity -The level of difficulty to build, solve or
understand something based on the number of inputs, interactions and
uncertainty involved.
Control Chart – The most powerful tool of statistical
process control. It consists of a run chart, together with
statistically determined upper and lower control limits and a
centerline.
Control Limits – Upper and lower bounds in a control chart
that are determined by the process itself. They can be used to detect
special or common causes of variation. They are usually set at ±3
standard deviations from the central tendency.
Correlation Coefficient - A measure of the linear relationship between two variables.
Cost of Poor Quality (COPQ) – The costs associated
with any activity that is not doing the right thing right the first
time. It is the financial qualification any waste that is not integral
to the product or service.
CP – A capability measure defined as the ratio of the specification width to short-term process performance width.
CPk. - An adjusted short-term capability index that
reduces the capability score in proportion to the offset of the process
center from the specification target.
Critical to Quality (CTQ) – Any characteristic that is critical to the perceived quality of the product, process or system. See Significant Y.
Critical X – An input to a process or system that exerts a significant influence on any one or all of the key outputs of a process.
Customer – Anyone who uses or consumes a product or service, whether internal or external to the providing organization or provider.
Cycle Time – The total amount of elapsed time expended from the time a task, product or service is started until it is completed.
Defect - An output of a process that does not meet a
defined specification, requirement or desire such as time, length,
color, finish, quantity, temperature etc.
Defective – A unit of product or service that contains at least one defect.
Deployment (Six Sigma) – The planning, launch, training and implementation management of a six sigma initiative within a company.
Design of Experiments (DOE) – Generally, it is the
discipline of using an efficient, structured, and proven approach to
interrogating a process or system for the purpose of maximizing the
gain in process or system knowledge.
Design for Six Sigma (DFSS) – The use of six sigma
thinking, tools and methods applied to the design of products and
services to improve the initial release performance, ongoing
reliability, and life-cycle cost.
DMAIC - The acronym for core phases of the six sigma
methodology used to solve process and business problems through data
and analytical methods. See define, measure, analyze, improve and
control.
DPMO – Defects per million opportunities – The total
number of defects observed divided by the total number of
opportunities, expressed in parts per million. Sometimes called Defects
per Million (DPM).
DPU – Defects per unit – The total number of defects detected in some number of units divided by the total number of those units.
Entitlement - The best demonstrated performance for an
existing configuration of a process or system. It is an empirical
demonstration of what level of improvement can potentially be reached.
Epsilon S – Greek symbol used to represent residual error.
Experimental Design – See Design of Experiments.
Failure Mode and Effects Analysis (FMEA) – A procedure used to identify, assess, and mitigate risks associated with potential product, system, or process failure modes.
Finance Representative – An individual who provides an
independent evaluation of a six sigma project in terms of hard and/or
soft savings. They are a project support resource to both Champions and
Project Leaders.
Fishbone Diagram – See cause and effect diagram.
Flowchart - A graphic model of the flow of activities, material, and/or information that occurs during a process.
Gage R&R - Quantitative assessment of how much
variation (repeatability and reproducibility) is in a measurement
system compared to the total variation of the process or system.
Green Belt – An individual who receives approximately
two weeks of training in DMAIC, analytical problem solving, and change
management methods. A Green Belt is a part time six sigma position that
applies six sigma to their local area, doing smaller-scoped projects
and providing support to Black Belt projects.
Hidden Factory or Operation – Corrective and
non-value-added work required to produce a unit of output that is
generally not recognized as an unnecessary generator of waste in form
of resources, materials and cost.
Histogram - A bar chart that depicts the frequencies (by the height of the plotted bars) of numerical or measurement categories.
Implementation Team – A cross-functional executive
team representing various areas of the company . Its charter is to
drive the implementation of six sigma by defining and documenting
practices, methods and operating policies.
Input - A resource consumed, utilized, or added to a process or system. Synonymous with X, characteristic, and input variable.
Input-Process-Output (IPO) Diagram – A visual
representation of a process or system where inputs are represented by
input arrows to a box (representing the process or system) and outputs
are shown using arrows emanating out of the box.
lshikawa Diagram – See cause and effect diagram and fishbone diagram.
Least Squares – A method of curve-fitting that defines
the best fit as the one that minimizes the sum of the squared
deviations of the data points from the fitted curve.
Long-term Variation – The observed variation of an
input or output characteristic which has had the opportunity to
experience the majority of the variation effects that influence it.
Lower Control Limit (LCL) - for control charts: the
limit above which the subgroup statistics must remain for the process
to be in control. Typically, 3 standard deviations below the central
tendency.
Lower Specification Limit (LSL) – The lowest value of a characteristic which is acceptable.
Master Black Belt – An individual who has received
training beyond a Black Belt. The technical, go-to expert regarding
technical and project issues in six sigma. Master Black Belts teach and
mentor other six sigma Belts, their projects and support Champions.
Mean – See average.
Measurement – The act of obtaining knowledge about an event or characteristic through measured quantification or assignment to categories.
Measurement Accuracy – For a repeated measurement, it is a comparison of the average of the measurements compare to some known standard.
Measurement Precision – For a repeated measurement, it is the amount of variation that exists in the measured values.
Measurement Systems Analysis (MSA) – An assessment of the accuracy and precision of a method of obtaining measurements. See also Gage R&R.
Median – The middle value of a data set when the values are arranged in either ascending or descending order.
Metric – A measure that is considered to be a key
indicator of performance. It should be linked to goals or objectives
and carefully monitored.
Natural Tolerances of a Process – See Control Limits.
Nominal Group Technique – A structured method that a team can use to generate and rank a list of ideas or items.
Non-Value Added (NVA) – Any activity performed in
producing a product or delivering a service that does not add value,
where value is defined as changing the form, fit or function of the
product or service and is something for which the customer is willing
to pay.
Normal Distribution – The distribution characterized by the smooth, bell- shaped curve. Synonymous with Gaussian Distribution.
Objective Statement – A succinct statement of the goals, timing and expectations of a six sigma improvement project.
Opportunities – The number of characteristics,
parameters or features of a product or service that can be classified
as acceptable or unacceptable.
Out of Control – A process is said to be out of
control if it exhibits variations larger than its control limits or
shows a pattern of variation.
Output – A resource or item or characteristic that is the product of a process or system. See also Y, CTQ.
Pareto Chart – A bar chart for attribute (or categorical) data categories are presented in descending order of frequency.
Pareto Principle – The general principle originally
proposed by Vilfredo Pareto (1848-1923) that the majority of influence
on an outcome is exerted by a minority of input factors.
Poka-Yoke - A translation of a Japanese term meaning to mistake-proof.
Probability – The likelihood of an event or circumstance occurring.
Problem Statement – A succinct statement of a business
situation which is used to bound and describe the problem the six sigma
project is attempting to solve.
Process - A set of activities and material and/or
information flow which transforms a set of inputs into outputs for the
purpose of producing a product, providing a service or performing a
task.
Process Characterization – The act of thoroughly
understanding a process, including the specific relationship(s) between
its outputs and the inputs, and its performance and capability.
Process Certification – Establishing documented evidence that a process will consistently produce required outcome or meet required specifications.
Process Flow Diagram – See flowchart.
Process Member – A individual who performs activities within a process to deliver a process output, a product or a service to a customer.
Process Owner – Process Owners have responsibility for
process performance and resources. They provide support, resources and
functional expertise to six sigma projects. They are accountable for
implementing developed six sigma solutions into their process.
Quality Function Deployment (QFD) – A systematic
process used to integrate customer requirements into every aspect of
the design and delivery of products and services.
Range - A measure of the variability in a data set. It is the difference between the largest and smallest values in a data set.
Regression Analysis - A statistical technique for
determining the mathematical relation between a measured quantity and
the variables it depends on. Includes Simple and Multiple Linear
Regression.
Repeatability (of a Measurement) – The extent to which
repeated measurements of a particular object with a particular
instrument produce the same value. See also Gage R&R.
Reproducibility (of a Measurement) – The extent to
which repeated measurements of a particular object with a particular
individual produce the same value. See also Gage R&R.
Rework - Activity required to correct defects produced by a process.
Risk Priority Number (RPN) – In Failure Mode Effects
Analysis — the aggregate score of a failure mode including its
severity, frequency of occurrence, and ability to be detected.
Rolled Throughput Yield (RTY) – The probability of a unit going through all process steps or system characteristics with zero defects.
R.U.M.B.A. - An acronym used to describe a method to
determine the validity of customer requirements. It stands for
Reasonable, Understandable, Measurable, Believable, and Achievable.
Run Chart – A basic graphical tool that charts a characteristic’s performance over time.
Scatter Plot – A chart in which one variable is plotted against another to determine the relationship, if any, between the two.
Screening Experiment - A type of experiment to identify the subset of significant factors from among a large group of potential factors.
Short Term Variation – The amount of variation
observed in a characteristic which has not had the opportunity to
experience all the sources of variation from the inputs acting on it.
Sigma Score (Z) – A commonly used measure of process
capability that represents the number of short-term standard deviations
between the center of a process and the closest specification limit.
Sometimes referred to as sigma level, or simply Sigma.
Significant Y – An output of a process that exerts a significant influence on the success of the process or the customer.
Six Sigma Leader – An individual that leads the
implementation of Six Sigma, coordinating all of the necessary
activities, assures optimal results are obtained and keeps everyone
informed of progress made.
Six Sigma Project - A well defined effort that states a business problem in quantifiable terms and with known improvement expectations.
Six Sigma (System) – A proven set of analytical tools,
project management techniques, reporting methods and management
techniques combined to form a powerful problem solving and business improvement methodology.
Special Cause Variation – Those non-random causes of variation that can be detected by the use of control charts and good process documentation.
Specification Limits – The bounds of acceptable performance for a characteristic.
Stability (of a Process) – A process is said to be stable if it shows no recognizable pattern of change and no special causes of variation are present.
Standard Deviation – One of the most common measures of variability in a data set or in a population. It is the square root of the variance.
Statistical Problem – A problem that is addressed with facts and data analysis methods.
Statistical Process Control (SPC) – The use of basic
graphical and statistical methods for measuring, analyzing, and
controlling the variation of a process for the purpose of continuously
improving the process. A process is said to be in a state of
statistical control when it exhibits only random variation.
Statistical Solution – A data driven solution with known confidence/risk levels, as opposed to a qualitative, “I think” solution.
Supplier – An individual or entity responsible for providing an input to a process in the form of resources or information.
Trend - A gradual, systematic change over time or some other variable.
TSSW – Thinking the six sigma way – A mental model for
improvement which perceives outcomes through a cause and effect
relationship combined with six sigma concepts to solve everyday and
business problems.
Two-Level Design – An experiment where all factors are set at one of two levels, denoted as low and high (-1 and + 1).
Upper Control Limit (UCL) for Control Charts – The
upper limit below which a process statistic must remain to be in
control. Typically this value is 3 standard deviations above the
central tendency.
Upper Specification Limit (USL) – The highest value of a characteristic which is acceptable.
Variability – A generic term that refers to the
property of a characteristic, process or system to take on different
values when it is repeated.
Variables – Quantities which are subject to change or variability.
Variable Data – Data which is continuous, which can be meaningfully subdivided, i.e. can have decimal subdivisions.
Variance – A specifically defined mathematical measure
of variability in a data set or population. It is the square of the
standard deviation.
Variation – See variability.
VOB – Voice of the business – Represents the needs of
the business and the key stakeholders of the business. It is usually
items such as profitability, revenue, growth, market share, etc.
VOC – Voice of the customer – Represents the expressed
and non-expressed needs, wants and desires of the recipient of a
process output, a product or a service. Its is usually expressed as
specifications, requirements or expectations.
VOP – Voice of the process – Represents the
performance and capability of a process to achieve both business and
customer needs. It is usually expressed in some form of an efficiency
and/or effectiveness metric.
Waste – Waste represents material, effort and time
that does not add value in the eyes of key stakeholders (Customers,
Employees, Investors).
X – An input characteristic to a process or system. In
six sigma it is usually used in the expression of Y=f(X), where the
output (Y) is a function of the inputs (X).
Y – An output characteristic of a process. In six
sigma it is usually used in the expression of Y=f(X), where the output
(Y) is a function of the inputs (X).
Yellow Belt - An individual who receives approximately
one week of training in problem solving and process optimization
methods. Yellow Belts participate in Process Management activates,
participate on Green and Black Belt projects and apply concepts to
their work area and their job.
Z Score – See Sigma Score.
