Six Sigma is a data-driven methodology that seeks to improve business processes in order to deliver high-quality products or services. Its purpose is to recognize and then remove defects from business processes, such as manufacturing. Six Sigma uses many quality management programs, such as statistical analysis, to carry out its process. Six Sigma processes are defined in sequential steps and followed strictly. (For related reading, see: Lean Six Sigma.)

Six Sigma certifications include: Yellow Belt, Green Belt, Black Belt and Master Black Belt. The courses can be found online, as well as through certified instructors. Unlike many other certifications for other professions, there is no standard certification body for Six Sigma. Different certification services are offered by various quality associations, such as American Society for Quality (ASQ) and other providers.

The criteria for Green Belt and Black Belt certification vary from organization to organization. For example, one organization might require only passing of the exam for the Green Belt certificate, whereas another organization might require work experience, as well. The service sector organizations that offer Six Sigma exams might alter the course structure due to different application needs of the organization. (For more, see: What is the Difference Between Lean Six Sigma and Six Sigma.)

At the basic level, the courses of Green Belt certificate are built upon:

  • an introduction of Six Sigma in an organization;
  • an understanding the objectives of the organization and the six sigma project;
  • Lean concepts and tools;
  • DMAIC (Define, Measure, Analyze, Improve and Control).

DMAIC is at the core of all Six Sigma projects and, thus, the core of all the Six Sigma certificate courses. The steps are briefly discussed below.


The purpose of this step is to define and describe process components and boundaries; identify owners, customers and other stakeholders; define and plan project scope and metrics; and define team dynamics and tools.


This step involves identifying and measuring the gap between current performance and the required performance. The measurement process is assessed, as well, to determine how accurate and precise it is.


This is when complex analysis tools, commonly the fish bone diagram and the pareto chart, are used to determine the root causes for elimination. The causes are listed and prioritized.  


After identifying and analyzing the root problems, they are either improved or eliminated. Solutions are identified. If the solutions are obvious, they are implemented right away, otherwise a detailed implementation plan is designed.


After implementing the solutions, the purpose is to sustain it. At times, a control plan is documented.

Bottom Line

Those with Green Belt certification usually work under the supervision of Black Belt or Master Black Belt-certified professionals. Green Belt certification is most suitable for mid-level project management team members, operation management personnel, consultants and engineers. (For related reading, see: Total Quality Management.)