Understanding the Basics of Six Sigma
The basic concepts contained within the Six Sigma methodology are of probability and statistics. Simply put, they equate to the level of confidence one can have in being completely certain planned business events will actually transpire in the planned fashion.
The ideas of measuring and improving processes and how near one comes to being able to deliver upon the implemented plan are important with this quality improvement strategy. Any variation will have ramifications upon the outcome. Whether or not these ramifications will affect the plan in the way intended is not always certain, so controls are needed to track the process improvement and make the necessary people aware of a potential problem before it becomes so large as to cause significant losses.
While it is only common sense that we are not able to guarantee that every outcome will occur exactly as we plan, it is apparent that we should think in the realm of ranges or percentages of acceptability within the planned action when it comes to Six Sigma. This is like a tolerance limit but instead of a tolerance being applied to the physical dimensions of a part, it is being applied to the overall process and the final acceptability level for the end user, namely the consumer.
These variations are measured along lines called distribution curves. If you have ever taken a class on statistics, you might be familiar with this medium of measuring and tracking. While the distribution curves will not alert us to what the process will accomplish next, they can be used to try to project a possible outcome based upon trends and probabilities.
When we group these probabilities into multiple segments within the distribution curve, they are called the standard deviation from the mean. Statisticians use the Greek letter sigma to represent this deviation standard. The process of Six Sigma is a way to demonstrate that the expected standard deviation from the mean is to be no more than 0.1% or 99.9%+ defect free in production processes.
If this range or tolerance limit for your production process is inside of this expectation, you will be able to rest well, knowing that you are and will continue to produce acceptable and quality products each and every cycle from the machine or process that produces the widgets. There must be controls in place to ensure that the target range or tolerance limit is not exceeded. The physical law of entropy shows us that things tend to work from a state of order to a state of disorder, so we must be sure to plan for routine maintenance and failure points.
When we allow for these things inside of our expectations, we will be able to produce high quality widgets in an efficient manner helping to promote a better bottom line of profitability for the company with the Six Sigma Methodology. In order to achieve near perfect results, the capabilities on the curve must be contained inside the tolerances beyond six standard deviations. This is also known as Six Sigma (six for the standard deviations and Sigma for the Greek symbol for standard deviations).
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