DFSS methods and uses for product- and process-oriented research and development

Although the mathematical history of standard deviation goes back to the eighteenth century, using standard deviation as a measurement standard dates to the 1920s when Walter Shewhart theorized that plus or minus three sigmas from the mean (93.32%) is the point where a process requires correction (Stamatis 2004). This would represent 66,807 DPM units. Six Sigma is a trademark of Motorola who in the 1980s developed the Six Sigma standard and the methodology associated with it. The company has documented over $16 billion in savings using the Six Sigma methodologies.