Six Sigma programs utilize advanced statistical methods to improve quality by reducing defects and variability in the performance of business processes. are based on three principles: (1) all work is a statistically controllable process; (2) no well-controlled process allows variability; and (3) defect-free work requires tight statistical controls. consist of a disciplined, statistics-based system aimed at producing not more than 2.5 defects per million iterations for a manufacturing or assembly process. radically redesign and streamline how an activity is performed. suggest that all activities can be controlled, employee empowerment is the best control tool, and 100 percent control is possible.