Six Sigma actually has several different facets to its meaning. First, if we look simply at the term Six Sigma, sigma represents standard deviation, which a universally accepted metric that allows us to calculate how much variability there is within a process. We then can use this information to determine if that process is able to stay within the established quality limits that have been set by our customer. Organizations use Six Sigma as a way to then measure the quality and performance of their processes. The sigma scale measures defects per million opportunities, or DPMO, and Six Sigma equates to 3.4 defects per million opportunities. Which is an extremely high level of quality.
In addition to being a metric, Six Sigma is also a five phase continuous improvement methodology. The methodology follows the Define, Measure, Analyze, Improve and Control or it's called by its acronym the DMAIC methodology. This methodology focuses on identifying improvement opportunities, analyzing current processes. And then finding different improvement solutions, implementing them, and then maintaining control of those improvements.
Finally, Six Sigma is also an organizational system that's used at a strategic level. Six Sigma is more than a set of metric based problem solving and process improvement methodologies. It's a continuous business improvement process that focuses on four key areas. Those are, understanding customer driven improvements, analyzing those current processes and services, aligning those processes to achieve those customers' requirements. And then finally, ensuring stability and sustainability of quality in the processes.
Six Sigma initiatives start with an organization deciding that they will need to change and improve. At this point, small improvement projects whether it's opportunities for improvement are identified and launched. These small initial projects are typically three to six months in duration. And they're often headed by a black belt. Although sometimes, Six Sigma green belts might need to implement smaller improvement projects. These projects go through the DMAIC stages, and their focus is on reducing cycle time, errors, cost, or improving a process in other ways.