How Six Sigma Works

Six Sigma Implementation

Image courtesy William Harris

In large companies with global supply and manufacturing operations, implementing Six Sigma is no small feat. There are generally two ways it happens. One way is through a separate organization that provides Six Sigma services to the main business. In this model, all Six Sigma projects run through the independent organization, making it easy to measure the impact of the changes. However, this arrangement can create a "we versus them" mentality that can undermine the effectiveness of the Six Sigma initiatives.

To avoid this tension, other companies take a more integrated approach. In this model, Six Sigma is incorporated into every employee's job, with a few highly trained experts acting as facilitators. This makes it more challenging to measure the impact of Six Sigma, but it helps create a culture in which a commitment to quality and excellence is pervasive.


Either way, Six Sigma relies heavily on teams of people working together, not on individual effort. A team can vary, but it will often include Six Sigma experts, process experts, data specialists, communicators and customers. A customer, in this case, refers to any person, internal or external, who is affected by a process or product change. This could be a person on the production line, someone in sales or marketing, a distributor or the ultimate end-user of a product or service. In fact, the customer may be the most important person on the team, because it is the customer who defines quality. It is his or her expectation of performance, reliability, competitive prices or on-time delivery that sets the bar.

Another critical role is that of team leader. The leader of a Six Sigma project must be extremely proficient in the technical aspects of Six Sigma statistics and process. If a project requires a high degree of Six Sigma expertise, it will be led by a Black Belt, a term borrowed from martial arts. Black Belts possess deep knowledge of all Six Sigma methods and tools and are assigned to lead projects that return a bottom-line value of $150,000 to an organization. If a project isn't as complex, it will be led by a Green Belt. Green Belts are qualified to solve the majority of process problems that arise in manufacturing environments and can always consult with Black Belts if they come up against a particularly challenging problem.

Yellow Belts represent everyone else on the team. They're not immersed in the details of the project and therefore don't require the same level of Six Sigma training or skill. That said, though, Yellow Belts are essential. They do apply some elements of the Six Sigma methodology as they help the Green Belt meet project goals and objectives. Yellow Belts are staff members, administrators, operations personnel and anyone else who might play a role.

Next, we'll learn about the DMAIC model for process improvement.