Six Sigma is a statistical approach which aims to drive up profits by putting extra special effort into ensuring goods or services conform to specification
As with SPC – Statistical Process Control – it’s applicable to repetitive processes but some goods and service organisations need much higher precision with their outputs if they are to meet acceptable standards for reliability or service
Hence, it’s not only about eliminating unpleasant surprises and broken promises by:
Reducing variation in the outputs from processes – defects or delivery times say – by ensuring virtually all meet certain minimum standards
Reducing waste and inefficiency
Redesigning a company’s products and internal processes so that customers get what they want, when they want and when they were promised
But getting things right 99% of the time is often not good enough if one has thousands of customers:
Deliveries to homes must be made when customers are in and waiting, not an hour or two later when they’ve had other appointments
Personal computers must work every time when millions switch them on, not 99 times out of 100
Airlines must not lose any of their passengers’ luggage
Hospitals must not make mistakes with in-patients
Six Sigma is SPC – Statistical Process Control – but with much stricter control limits:
SPC usually requires some 99.97% of the output from any process to fall within three standard deviations of the average for customer acceptability– 0.03% may fall outside this range – 3 defective items in every 10,000
Six Sigma aims for no more than 3.4 defects in every 1,000,000, covered by a range of 6 standard deviations from the average
The latter maximum failure rate is vital for a company like Intel – imagine if you bought a computer which often didn’t work because of a dodgy chip they’d made
