Six Sigma relates to the defect rate per million as a quality measure. It is like a “Richter scale” for quality, where higher numbers are better. For example, 6 sigma capability (sometimes called a sigma rating or sigma quality level) means that over the long run, we have no more than 3.4 defects per million (or a 99.9996% first-pass yield). From benchmarking that the Six Sigma Research Institute did, they found this to be world-class. An average process measures around 4 sigma capability and 6,210 defects per million. Think about airline baggage handling. They lose or misroute about 6,000 bags per million annually, so they are about average on the sigma capability scale. Our goal is to strive toward world-class.