Six Sigma

Six Sigma is a systematic method of quality management which aims to improve processes through analytical and mathematical approaches and avoid or reduce errors. In mathematics, Sigma describes the standard deviation from the normal distribution. In marketing, the Six Sigma method measures a company's error rate using the sigma level. The Six Sigma level corresponds to the zero-error principle, i.e. the closer a process
comes to the Six Sigma level, the fewer errors the process has.