Gatlin Education Six Sigma Green Belt - OVERVIEW Why Do Six Sigma - Page 14

DPMO vs. Error Rate You might wonder why the DPMO acronym is used, rather than a simple yield or a simple defect rate. As we move beyond a 3 Sigma level of performance, such as found in a typical process for an average company, the defect rates get small fairly rapidly. At 4 Sigma, the defect rate is less than one percent. We can see that the DPMO terminology is simply a matter of convenience.