Six Sigma

One method of preparing and controlling the compliance of processes and products with predetermined quality standards. 

Six Sigma at many organizations simply means a measure of quality that strives for near perfection. Six Sigma is a disciplined, data-driven approach and methodology for eliminating defects (driving toward six standard deviations between the mean and the nearest specification limit) in any process. To achieve Six Sigma, a process must not produce more than 3.4 defects per million opportunities.