Six Sigma is a statistical methodology that measures the number of deviations or inconsistencies in a process per million opportunities. The higher the Sigma level, the lower the error or defect rate. The purpose is to measure the number of defects, identify the size of the opportunity for improvement and set a focused course of action.
Understanding Sigma Levels1
| Sigma Level |
DPMO Defects per Million Opportunities |
Number of Misspelled Words | Accuracy |
|---|---|---|---|
| 1 | 690,000 | 159 per page | 30.9% |
| 2 | 308,000 | 23 per page | 69.2% |
| 3 | 66,800 | 1.35 per page | 93.3% |
| 4 | 6,210 | 1 per 31 pages | 99.4% |
| 5 | 320 | 1 per several books | 99.98% |
| 6 | 3.4 | 1 per small library | 99.9997% |
It is rare for any activity in healthcare to reach Six Sigma quality. In all areas of healthcare, the opportunities for quality improvement abound.
Is a goal of 99.7% accuracy good enough?
99.7% accuracy means:
- 20,000 lost pieces of mail per hour
- More than 300,000 babies dropped by doctors and nurses each year
- Unsafe drinking water for nearly 15 minutes per day
- 5,000 incorrect surgical operations per week
- Short or long landings at most major airports daily
- No electricity for almost seven hours a month
