Alternative Hypothesis (Ha): Used during hypothesis testing, the opposite of the Null Hypothesis.

ANOVA: Analysis of Variance

Attribute Data (Category Data): A type of data that cannot but sub-divided further (eg. pass / fail).

Average: The middle value of a sample set of data. Calculated by adding all results & divided by sample size.

Baseline: The current performance value of a process before improvements are made.

Bias: A consistent value between true and measured values.

Continuous Data: A type of data which can be measured (eg. distance).

Critical to Quality (CTQ): Features of a product or service that are critical to quality from the customer's perspective.

Defect: A feature of a product or service that does not meet with customer expectations.

Design of Experiments (DOE): A range of controlled experiments used to identify the relationship between inputs & outputs of a process.

DFSS: Design for six sigma.

DMADV: Define, measure, analyse, design & verify.

DMAIC: Design, measure, analyse, improve & control.

DOE: Design of experiment.

DPMO: Defects per million opportunities.

FMEA: Failure mode & effect analysis.

Hypothesis Testing: Taking a decision from a data set based on statistical confidence.

KPI: Key performance indicator.

LSL: Lower specification limit

Mean: Same as the average (middle value) of a set of data.

Normal Distribution: A symmetrical (bell shaped) distribution.

Null Hypothesis (Ho): Used in hypothesis testing, the primary assumption or theory when testing a data set (opposite of Alternative Hypothesis).

Process Capability: The ability of a process to meet customer requirements.

QFD: Quality function deployment.

Root Cause: Overriding reason for a defect or issue occurring.

Sample: A collection of data measurements taken form a process.

Sample Size: Number of data points in a sample.

Sigma Level: Measure of process capability.

SIPOC: Suppliers, inputs, process, outputs, customers.

Standard Deviation: A measure of the average variation of a sample set of data points from their own average.

USL: Upper specification limit.

Voice of the Customer (VOC): Feedback from the customer about acceptable level of standard of product or service.

Z Value: The distance (standard deviation) between a process average & the upper specification limit.