Six Sigma Glossary

Six Sigma Glossary

Benchmarking
An improvement process whereby a company measures its performance against that of best-in-class companies, determines how those companies achieved their performance levels, and uses the information to improve its own performance.
Black Belt
Full-time Six Sigma project leader who is certified following a four-month training and application program and successful completion of two Six Sigma Projects, the first under the guidance of a Master Black Belt, the second more autonomously.
DMAIC
The data driven, Six Sigma process improvement strategy involving 5 phases:
Define, Measure, Analyze, Improve and Control.
Cause
That which produces an effect or brings about change.
Cause-And-Effect Diagram
A schematic sketch, usually resembling a fishbone, which illustrates the main causes and subcausesleading to an effect (symptom). Also known as Fishbone Diagram.
Champion
Normally senior staff of the company who has undergone extensiveSix Sigma training. Champions provide direction, resources and support tothe Six Sigma effort and pprove and review projects.
Characteristic
A definable or measurable feature of a process, product or variable.
Control Chart
A graphical rendition of a characteristic’s performance across time in relation to its natural limits and central tendency.
Correlation
The determination of the effect of one variable upon another in a dependent situation.
Cp
A widely used capability index for process capability studies. It may range in value from zero to infinity with a larger value indicating a more capable process. Six Sigma represents Cp of 2.0.
Cpk
An index combining Cp and K (Difference between the process meanand the specification mean) to determine whether the process will produce units withintolerance.Cpkis always less than or equal to Cp. When the process is centered at nominal,Cpkis equal to Cp.
Critical To Quality (CTQ)
An element of a design or a characteristic of a part that is essential to quality in the eyes of the customer, formerly known as a key quality characteristic (KQC).
Data
Factual information used as a basis for reasoning, discussion orcalculation; often refers to quantitative information.
Defect
A failure to meet an imposed requirement on a single quality characteristic or a single instance of nonconformance to the specification.
Defects Per Million Opportunities (DPMO)
The number of defects counted, divided by the actual number of opportunities to make a defect, then multiplied by one million. A direct measure of sigma level.
Defects Per Unit (DPU)
The number of defects counted, divided by the number of productsor characteristics produced. A process of counting and reducing defects as an initial step toward Six Sigma quality.
Defective
A unit of product containing one or more defects.
Design For Manufacturability (DFM)
A concept in which products are designed within the current manufacturing process capability to ensure that engineering requirements are met during production.
Design of Experiments (DOE)
Statistical experimental designs to economically improve productand process quality. A major tool used during the “Improve Phase”of Six Sigma methodology.
Distributions
Tendency of large numbers of observations to group themselves around some central value with a certain amount of variation or “scatter”on either side.
Effect
That which was produced by a cause.
Experiment
A test under defined conditions to determine an unknown effect; to illustrate or verify a known law; to test or establish a hypothesis.
Experimental Error
A test under defined conditions to determine an unknown effect; to illustrate or verify a known law; to test or establish a hypothesis.
“Factory”Processes
For Six Sigma purposes, defined as design, manufacturing, assembly or test processes which directly impact hardware (see also transaction processes).
Fishbone Diagram
A schematic sketch, usually resembling a fishbone, which illustrates the main causes and subcauses leading to an effect (symptom). Also known as Cause-And-Effect Diagram.
Failure Mode Effects Analysis (FMEA)
A process in which each potential failure mode in every sub-item of an item is analyzed to determine its effect on other sub-items and on the required function of the item.
“Five ME”
Major sources of variation: manpower, machine, method, materialand measurement. Additionally, “environment”is considered to be a source of variation.
Frequency Distribution
The pattern or shape formed by the group of measurements in a distribution.
Gage Repeatability & Reproducibility (Gage R&R)
A measurement system evaluation to determine equipment variationand appraiser variation. This study is critical to ensure that the collected data is accurate.
Histogram
Vertical display of a population distribution in terms of frequencies; a formal method of plotting a frequency distribution.
Independent Variable
A controlled variable; a variable whose value is independent of the value of another variable.
Interaction
When the effects of a factor A are not the same at all levels ofanother factor B.
Lower Control Limit
A horizontal dotted line plotted on a control chart which represents the lower process limit capabilities of a process.
Master Black Belt
An expert in quality techniques specially trained to advise leaders, facilitate quality teams and accelerate process improvement. Master Black Belts select, train and mentor Black Belts; develop and implement the Six Sigma deployment plan; and select and ensure completion of Six Sigma projects.
Nonconformity
A condition within a unit which does not conform to some specification, standard, and/or requirement; often referred to as a defect; any given nonconforming unit can have the potential for more than one nonconformity.
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