Widely referred to as ‘Six Sigma’, the six sigma method started in production and has been developed as a business management strategy. Six sigma enjoys widespread application in many industries. It seeks to ensure that every process delivers stable and predictable results by removing the causes of errors. It recognises that every process has a degree of variation, and expects the variation to be measured, and the causes of variation to be understood. The method quantifies the allowed variation using the statistical term sigma – six sigma in effect means 3.4 defects per million opportunities.