Six Sigma

Six Sigma

A data-driven methodology for reducing variation and defects to no more than 3.4 per million opportunities.

Six Sigma is a disciplined, statistical approach to quality improvement that aims to reduce process variation until defects fall to 3.4 per million opportunities (a 6σ level). It uses the DMAIC roadmap and a belt-based certification structure.

Where lean attacks waste and speed, Six Sigma attacks variation and defects with tools like SPC, DOE, and capability analysis. Combined, they form Lean Six Sigma.

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Six Sigma guide→DPMO / Sigma Calculator→
Related Terms
Lean Six Sigma
A methodology combining lean's focus on flow and waste with Six Sigma's focus on reducing variation and defects.
DMAIC
The five-phase data-driven improvement cycle at the heart of Six Sigma for improving existing processes.
SPC
Using control charts to monitor a process and distinguish normal variation from special-cause signals requiring action.
Process Capability
Indices (Cp, Cpk) that compare the spread and centering of a process to its specification limits.
DPMO
A normalized defect metric that allows fair comparison of quality across processes of different complexity.
Sigma Level
A measure of process capability expressed in standard deviations between the mean and the nearest spec limit.

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