When learning about Six Sigma, it may help to consider these charts, which detail how sigma level relates to defects per million opportunities (DPMO), and some real-world examples.
Sigma Performance Table
| Sigma Performance Levels – One to Six Sigma | ||
|---|---|---|
| Sigma Level | Defects (or Errors) Per Million Opportunities (DPMO) | Yield (or Produced or Delivered) Correctly (%) |
| 1 | 691,462 | 30.85 |
| 2 | 308,538 | 69.146 |
| 3 | 66,807 | 93.319 |
| 4 | 6,210 | 99.379 |
| 5 | 233 | 99.9767 |
| 6 | 3.4 | 99.9997 |
What Would Sigma Values Look Like In The Real World?
It’s one thing to see the numbers and it’s a whole other thing to see how it would apply to your daily life.
| Real-world Performance Levels | |||
|---|---|---|---|
| Situation or Example | In 1 Sigma World | In 3 Sigma World | In 6 Sigma World |
| Pieces of your mail lost per year [assuming 1,600 opportunities per year] | 1,106 | 107 | Less than 1 |
| Number of aircraft takeoff or landing incidents [assuming one takeoff and landing per flight, round trip] | 25 times per 10 flights | 24 times per 100 flights | 12 times per million flights |
| Number of empty coffee pots at work (who didn’t fill the coffee pot again?) [assuming 680 opportunities per year] | 470 | 45 | Less than 1 |
| Number of telephone disconnections [assuming 7,000 talk minutes] | 4,839 | 467 | 0.02 |
| Erroneous business orders [assuming 250,000 opportunities per year] | 172,924 | 16,694 | 0.9 |
| Electricity outage [assuming 30 day month = 720 hours] | 500 hours | 45 hours | 9 minutes |
In the United States alone if the sigma level were between 3 and 4, there would be 50 newborn babies dropped per day and 5,000 incorrect surgical procedures per week.
Not all opportunities and defects are created equal. I think all flight passengers would agree that a flight delay is less worrisome than a flight incident on landing.
