Much has been said about Six Sigma and the benefits and savings it brings to every organization. The latest to join the roster of successful companies that turn to Six Sigma are 3M, Starwood Hotels, Sears, Home Depot, Bank of America, JPMorgan Chase, a city government, and John Hopkins Medical.
According to Peter Peterka, the leading consultant for 6sigma.us, Six Sigma?s success revolves around the fundamental elements needed for any successful organization. Once the organization has created their own vision of Six Sigma, the business leaders need to define their organization?s objectives in numerical terms. These ?high-level metrics,? often called big Y?s in Six Sigma, are the foundation for identifying project y?s that Six Sigma Belts will execute projects on. With big Y?s in hand, business leaders called Six Sigma Champions breakdown these organizational level Y?s into smaller y?s that a project leader called a Green Belt or Black Belt can work from. Once an organization has decided on the method and the project y?s, Belts are marched off to training ?waves? bringing management-approved projects to class. DMAIC Green Belt training is normally two one-week sessions separated by one month. Black Belt training waves are extended by two additional months with two more weeks of training. The emphasis during the extended two weeks of Black Belt training is often on learning more details about advanced tools such as Design of Experiments (DOE).
People might be surprised that the DOE fits into the Six Sigma methodology. But there is such a connection. Six Sigma is about understanding and controlling the variation of key process variables known as inputs or x?s to obtain improved results on project outputs or y?s. Design of Experiment terms on the other hand treat these inputs or x?s as factors and the outputs as responses. In nearly all Six Sigma projects the relationship of the project y?s takes on the form of y=f(x1,x2,…xn). In Six Sigma terms it is discovering the relationship between outputs called y?s and inputs called x?s.
Present Six Sigma Belts therefore focus their use of Design of Experiments in the Improve phase of DMAIC and the Optimize phase of IDOV. And during the DMAIC Six Sigma training, they learn two of the common experimental designs: factorial and fractional factorial designs. In some trainings, too, the curricula include the response-surface designs and optimization designs at a high level. DFSS includes the experimental designs in all levels of DMAIC training and expands to include the concept of robust designs. A number of consulting companies also teach Taguchi designs.
Peterka further observes, “As Six Sigma professionals learn more about the power of properly planned experiments, Design of Experiments will be integrated into most phases of the Six Sigma roadmap and not just considered an advanced tool for the improvement and optimization phases. Experienced practitioners of statistical methods like Design of Experiments should learn the language of Six Sigma and help integrate new methods into the Six Sigma process to improve its effectiveness.
The Six Sigma Method and Design of Experiments
