The Cost of Poorly Performing Processes – Need for Six Sigma
April 3, 2025
Prior to the introduction of Six Sigma philosophy, there was a debate as to whether Six Sigma is a goal worth pursuing. Many experts in the area of quality believed that wastage was a way of life. Trying to eliminate wastage would cause more wastage. They believed that it was possible to eliminate waste but…
Definition of Six Sigma Six Sigma is not a mere methodology or a quality tool. It is a philosophy i.e. a systematic way of thinking to solve quality problems. Six sigma involves use of statistics to convert raw data into facts about how the processes of the organization are being run. The thrust is on…
Six Sigma has really become a management buzzword. A lot of people use it in very different contexts. As a result a variety of meanings have been conjured up for the very simple six sigma process. To simplify matters and to ensure that the readers have an accurate understanding of what the Six Sigma process…
Sigma or standard deviation is a statistical measure of dispersion in data. It is a measure which uses the characteristic of past data to make judgements about how the process will perform in the future. If a given set of data has normal probability distribution then the number of defects that will occur in the process over a period of time can be known depending upon the sigma level of the process.
The sigma (standard deviation) is multiplied with the numbers 1, 2, 3 etc to come up with a range. For example lets assume that the average of a data set is 10, while the sigma is 2. Hence 1 sigma will include all the data points between 10 +/-2 i.e. between 8 and 12. A 2 sigma measure would include 10+/-2(2) i.e. all data points between 6 and 14. So on and so forth.
However, it is a known fact that in a normal distribution the points tend to be around the mean. Therefore all the points will be closer to the average. Hence as one goes to farther and farther sigma levels the additional gains in terms of productivity are less.
To be a six sigma organization, the processes of an organization must be able to support this kind of efficiency sustainably. Building such robust processes requires a lot of intelligence and effort.
Sigma Level | Defects/Million | Percentage Defects |
1 | 691462 | 69% |
2 | 308538 | 31% |
3 | 66807 | 6.7% |
4 | 6210 | 0.62% |
5 | 233 | 0.023% |
6 | 3.4 | 0.00034% |
7 | 0.019 | 0.0000019% |
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