Six Sigma is a disciplined, data-driven methodology for eliminating defects in any process – from 制造业 to transactional and from product to service. The statistical representation of Six Sigma describes a process where 99.99966% of all opportunities to produce some feature of a part are statistically expected to be free of defects (3.4 defects per million opportunities).
Six Sigma seeks to improve the quality of process outputs by identifying and removing the causes of defects and minimizing variability in manufacturing and business processes. It uses a set of quality management methods, mainly empirical, statistical methods, and creates a special infrastructure of people within the organization (e.g., ‘Champions’, ‘Black Belts’, ‘Green Belts’) who are experts in these methods. Each Six Sigma project carried out within an organization follows a defined sequence of steps and has specific value targets, for example: reduce process cycle time, reduce pollution, reduce costs, increase customer satisfaction, and increase profits.
The two main project methodologies used are DMAIC (Define, Measure, Analyze, Improve, Control), which is used for projects aimed at improving an existing business process, and DMADV (Define, Measure, Analyze, Design, Verify), used for projects aimed at creating new product or process designs. The core of the methodology is the rigorous application of statistical tools like 统计过程控制 (统计过程控制), regression analysis, and design of experiments (DOE) to identify the root causes of variation and defects, and then to implement and sustain improvements.