Quality Management Tools

Six Sigma

CIMA Official Terminology describes Six Sigma as a methodology based on TQM to achieve very low defect rates. The ‘sigma’ refers to the Greek letter used to denote standard deviation, so ‘six sigma’ means that the error rate lies beyond six standard deviations from the mean. To achieve six sigma, an organization must therefore produce not more than 3.4 defects per million products.

In practice, businesses use techniques such as statistical process control to monitor and chart processes, identifying exceptions to the upper and lower limits and aiming to reduce the number of faults.