Six Sigma is a disciplined, statistical approach to eliminating defects and reducing variation in manufacturing and business processes. The name refers to the statistical concept of fitting six standard deviations between the process mean and the nearest specification limit, which translates to 3.4 defects per million opportunities (DPMO).
The primary Six Sigma methodology is DMAIC: Define the problem and goals, Measure current process performance, Analyze data to identify root causes, Improve the process by addressing root causes, and Control the improved process to sustain gains. Each phase uses specific statistical tools — process mapping, Pareto analysis, hypothesis testing, design of experiments, and control charts.
In manufacturing, Six Sigma projects typically target measurable outcomes: reducing scrap rates, improving first-pass yield, decreasing cycle time variation, or lowering warranty claims. The methodology requires reliable process data as its foundation — manufacturers with automated data collection from machines and inspection equipment can run Six Sigma projects far more effectively than those relying on manual data entry.