What is Six Sigma?

In statistics "sigma" refers to a variation. Six Sigma methodology focuses on reducing variation as a way to improve process. In particular, it uses sigma to measure the performance of a process to produce defect-free results. A defect is anything that causes customer dissatisfaction, such as a product that doesn't meet the customers specifications, poor service, or a price tag that's too high.

The term Six Sigma defines an optimum measurement of quality. A company operating at Six Sigma quality produces 3.4 defects per million opportunities; that is, the work is 99.999966% defect free. Today, most organizations operate between 2 and 3 sigma. Even the best companies in the world operate at the 99% perfect level. 99% perfect (3.8 sigma) is still 6,000 to 66,0000 defects per million.