Six Sigma eLearning Glossary of Six Sigma Terms (S - Z)

A - D

E - M

N -R

S - Z

Sample Size
The amount of data the experimenter needs to answer a statistical question.  Varies with alpha risk, beta risk & the associated difference to be detected.

Sample Statistic
A value derived from a sample from a population that is used to estimate the value of a population parameter or group characteristic.

Screening Experiments
Lower resolution designed experiments (DOE) for investigating main effects, usually involving several factors. Screening experiments often use Fractional Factorial designs.

Secondary Metric
Used to measure unintended consequences of process/product changes.

Shewhart
The inventor of control charts.

Shift
A sudden change in a process characteristic.

Six Sigma
Motorola Corporation originated Six Sigma during the 1980s as a quality management methodology, strategy, and tactics to enhance customer satisfaction, employee development, and continuously improve processes to increase corporate profits, shareholder value, and achieve corporate excellence.

Simple Regression
A method for determining an optimal equation (least-squared difference between observed and predicted values for the response) for a response as a function of just one input variable: Y= b0 + b1 X + error.

Special Cause Variation
Intermittent variation attributed to assignable events. Control charts are often used to distinguish between special cause variation and common cause variation.

Specification Limits
Requirements based on the customer requirements or expectations.

Stability of a Measurement System
A measure of the variation in accuracy or precision of a measurement system over time.

Standard Deviation
The square root of the variance.

Star and Axial Points
Levels of inputs in a Central Composite Design experiment used to determine the second order terms in Response Surface Modeling.

Steepest Ascent or Descent
A procedure for moving along the direction or combination of input factor values that most rapidly increases or decreases the value of the response.

Surface Plot
A plot for a Response or z-variable based on a mesh determined from two input factors, an x-variable and a y-variable.

Taguchi Quality Philosophy
The idea that any deviation from the target imparts a loss to society.

t-Distribution
Used for determining the confidence interval for means or for determining whether two means are significantly different. Developed by Gossett under the pseudonym ďStudent; hence, also referred to as Studentís t-distribution.

Temporal Variation
Time-to-time variation.

Transition Action Plan
The actions required to move the project from the Black Beltís control to the functional organizationís control.

Treatment
A single level assigned to a single factor.

Treatment Combination
An experiment run using a set of the specific levels of each input variable.

Type I Error
Finding an imagined difference where none actually exists.

Type II Error
Failing to find a difference when one actually exists.

Value-Added
An operation that transforms the product in a way that is meaningful to the customer.

VOB
Voice of the Business.

VOC
Voice of the Customer.

VOP
Voice of the Process.

Z-score
The distance of a particular value from the sample mean in units of standard deviations.
 

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