This topic addresses the concept of Defects Per Million Opportunities, or DPMO. As we’re able to measure and capture data about something, we can begin to chart it and evaluate its relative performance against a goal, or mean measurement. And using the methods for Six Sigma, we would begin to understand with the use of standard deviations, how our performance compares to that goal with respect to an upper or lower specification limit. Anything outside these limits will not meet the expectation for what it is we’re trying to produce and deliver to our customer. The chart includes the mean, or goal, while the increments further and further from the mean represent increasing standard deviations. While many operations may set a level of tolerance at 3 standard deviations, plus or minus from the mean. If our process is operating at a level of Six Sigma quality, we’re setting a much higher expectation of quality. An operation performing at a level of Six Sigma quality is 99.997% defect free, meaning only about three defects per million opportunities are expected. What is the difference between an operation where the deliverables are expected to fall within Three Sigma versus an operational that operates at Six Sigma? The difference may surprise you.
Here is the difference that Six Sigma makes when an operation is able to limit defects to only 3.4 per million opportunities in its processes. At Three Sigma this could mean losing 20,000 pieces of mail per hour. But with Six Sigma quality, only 7 pieces of mail are lost which is a monstrous improvement. What about 5,000 incorrect surgeries per week versus just 1.7? Or outages of electricity of almost 7 hours per month versus a very, very rare 1 hour every 34 years? How about drug prescriptions? 54,000 prescriptions that are wrong is way too many, considering it could be a matter of life and death. Six Sigma quality suggests that this should only happen only once every 25 years. How about landing airplanes? Thankfully airlines mostly operate at Six Sigma quality today. And as a result, we don’t see a lot of airplanes crashing. However, it would happen a lot if they only operated at three deviations or three sigma in their performance. Six Sigma is very adaptable and with a little bit of effort, any organization can work toward this level of performance. Six Sigma quality can affect every single industry that we work in, from manufacturing to consulting, profit to nonprofit, government to the private sector. A great application of Six Sigma quality can be evidenced in customer facing organizations like call centers and contact centers that serve customers. But there is no upper or lower limit in terms of the size or type of organization that can adapt and use Six Sigma successfully.