Six Sigma

Six Sigma

Six Sigma is a statistical approach which aims to drive up profits by putting special effort into ensuring goods or services conform to specification

Six Sigma is about eliminating unpleasant surprises and broken promises via:
- Reducing any 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

It’s not about averages but removing variation from customers’ interfaces with you

Getting things right 95% of the time is often just not good enough:
- Deliveries to your home must be made when you’re in and waiting, not an hour or two later when you’ve had to go back to work
- Personal computers must work when millions switch them on, every time, not 99 times out of 100
- Airlines must not lose luggage, hospitals must not make mistakes – for you

Six Sigma is Statistical Process Control with extremely strict control limits:
- SPC usually requires some 99.97% of the output from any process to fall within three standard deviations of the average – in other words 0.03% (3 defective items in every 10,000) may fall outside this range
- Six Sigma aims for no more than 3.4 defects per million – 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