Six Sigma

Six Sigma is a data-driven process improvement methodology aimed at eliminating defects in a process. Its target is a defect rate of 3.4 defects per million opportunities, a level corresponding to six standard deviations from the mean. Six Sigma projects follow the DMAIC sequence: Define, Measure, Analyze, Improve and Control.

Source checked2/2 values · 2026-10-25Methodology

Specification

1 source

Kind	methodology
Origin	Motorola, 1980s

Study notes

Sigma is the standard deviation, a measure of variability in a process.
The term Six Sigma refers to a process with a deviation of six standard deviations from the mean.
The target defect rate is 3.4 defects per million opportunities (DPMO).
A defect is defined as any process output that does not meet customer requirements.
Certification levels listed are white belt, yellow belt, green belt, black belt and master black belt.
Six Sigma projects use the DMAIC methodology: Define, Measure, Analyze, Improve and Control.
The methodology uses data to identify root causes of defects and implements solutions that eliminate them.
The name was first coined by Motorola in the 1980s to describe its quality control program.
The document states certification does not necessarily indicate capability.
The document states reliance on statistical analysis limits the number of people capable of effective practice, making training difficult to scale.
Example project goal: reduce average customer service call wait time to no more than 2 minutes.