An Introduction to Six Sigma

Today, customers expect only the highest quality and the utmost consistency with near zero defects. Because of how rapidly information can spread over the internet, even a relatively small misstep can be fatal for a company. Once customers get used to a certain standard of quality, any deviation from it is often perceived as unacceptable.

In 1986, two Motorola engineers, Bill Smith and Mikel J. Harry, wanted to reduce the total number of manufacturing defects. They came up with a data-driven approach and methodology for eliminating defects known as Six Sigma (sometimes stylized as 6σ). With it, they successfully reduced manufacturing defects to 3.4 defective features per million opportunities.

But it wasn’t until the 90s that Six Sigma established itself as one of the most popular management methodologies in history. In 1995, Jack Welch, chairman and CEO of General Electric between 1981 and 2001, made it central to his business strategy at General Electric, contributing over $300 million to GE’s operating income just two years after the start of the initiative.

Six Sigma has continued evolving over the years, and focuses on improving customer satisfaction, meeting stakeholders' requirements, and improving the outputs (products/services) offered by organizations.

Six Sigma Methodologies

Six Sigma relies on quality management methods to improve the quality of the output of a process. The goal is always to identify and remove the causes of defects and minimize inconsistency in manufacturing and business processes.

The fundamental six Sigma methodology aimed at improving existing business processes is called DMAIC, which stands for Define, Measure, Analyze, Improve, and Control, referring to its five phrases.

During the first phase, process goals are defined using key parameters based on identified requirements. Then relevant aspects of the current process are measured and quantified. An in-depth analysis of the measured data can reveal cause-and-effect relationships. When a cause is discovered, an improvement is implemented to reduce variation and eliminate defects. Finally, reliable control systems are put in place to control the future performance of the process and to ensure that any deviations are corrected before they result in defects.

For creating new product or process designs, a Six Sigma methodology known as DMADV is used instead. DMADV stands for Define, Measure, Analyze, Design, and Verify. It relies on an analysis of requirements elicited from customers and stakeholders. These requirements form the basis upon which design proposals are created. The proposals go through several iterations, which consist of analysis and improvements based on it, until the design is verified and handed over as a finished product.


What started in the 80s as an internal technique used by Motorola to improve their quality control has become one of the most popular management methodologies in the world. Today, Six Sigma is used by professionals across many different industries. In addition, six sigma certifications don’t go unnoticed by HR representatives in search of capable business analysts and quality specialists.