The Complete Guide to Six Sigma Methodology

Whether manufacturing physical products or providing digital services, most businesses follow some sort of process to deliver the proverbial goods. Six Sigma methodology is a simple yet broad way to improve and streamline business functions through maximum quality of output. However, Six Sigma is not without its criticisms, and project managers should be aware of the pros and cons of this system before implementing it. 

In this article, we’ll explain what the Six Sigma methodology is, how lean Six Sigma principles differ, and how Six Sigma project management can help boost your organization’s process efficiency and quality.

Six Sigma explained

At its core, Six Sigma is a quality improvement program. The Six Sigma methodology encompasses a set of tools and techniques designed to help organizations improve their business processes, increase performance, and decrease the rate of defects stemming from process variation. The term “Six Sigma” — capitalized because it is a registered trademark of Motorola — refers to a way of measuring a process to determine its yield or the percentage of defect-free products it creates. When Motorola set a goal of achieving Six Sigma in its manufacturing, it meant that the company was striving for less than 3.4 defects per million opportunities. 

The principles of Six Sigma were first introduced at Motorola by engineer Bill Smith in 1986. However, it was the adoption of the Six Sigma methodology by General Electric in the mid-90s that brought the system to the attention of the broader business world. GE has estimated that the adoption of Six Sigma concepts produced a $10 billion benefit in the first five years alone. 

Why Six Sigma is important to project management

Continually improving business processes and achieving as near-to-perfect as possible output quality should be a priority of any organization. As a proven quality program, the Six Sigma methodology can help project managers define, measure, analyze, and improve processes and ultimately achieve more predictable and reliable outcomes. 

To better understand why Six Sigma is important to project management, it helps to look at the methodology’s core doctrine. Six Sigma asserts that:

  • Business success hinges on the continuous effort to achieve stable, predictable process results 
  • Business processes have characteristics that can be defined, measured, analyzed, improved, and controlled
  • Achieving this continuous state of quality and process improvement requires commitment from the entire organization, especially top-level management

The Six Sigma process can help project managers identify, measure, and ultimately improve repeatable project processes to deliver the highest-quality deliverables as consistently as possible. 

What are the features of Six Sigma?

The Six Sigma project management methodology contains a few features that set it apart from other quality improvement programs. These features include: 

A focus on measurable, quantifiable financial returns on every project

A strong emphasis on engaged and passionate leadership

A commitment to basing decisions on verifiable data and statistics over assumptions or guesswork

What is the Six Sigma process?

The Six Sigma process consists of two distinct project methodologies: DMAIC and DMADV. Both methodologies have five phases, the first three of which are “define,” “measure,” and “analyze.” The key difference between these two methods is that DMAIC is used to improve existing business or project processes, while DMADV is used to create new processes.

When following the DMAIC method, the final two steps are “improve” and “control.” In the DMADV process, the final steps are “design” and “verify.” 

Introducing the DMAIC roadmap

While the Six Sigma methodology can be used to establish new business processes, it is most often used to improve and refine existing procedures. That’s why the DMAIC roadmap is considered the core tool in the Six Sigma toolbox.

The DMAIC roadmap consists of five phases or steps:

  1. Define
    The first step in the Six Sigma process is to define the business problem and project objective, goal, and scope, as well as needed resources and a timeline for completion. This information should be captured by your project charter as well. 
  2. Measure
    The second step is to measure as many aspects of the current process as possible so that you can establish a baseline. The data you collect during this stage will then be measured against future projects to determine process improvement metrics.
  3. Analyze
    One major aspect of process improvement is the elimination of any steps that are hindering or preventing progress. During Six Sigma’s analysis phase, you will review all the data you have collected and measured to identify these problematic aspects and remove or modify them as needed.
  4. Improve
    With the problem areas identified, it’s time to develop, implement, and test solutions to those issues. Ideally, you want to eliminate the root source of the problem and establish safeguards to prevent them from rearing their ugly heads again. 
  5. Control
    The final step in the Six Sigma process is to ensure that the improvements you’ve implemented are sustainable. This is achieved with a control plan, which codifies the procedures you’ve established to maintain the new, higher level of output quality. 

A look at the lean Six Sigma principles

Lean Six Sigma combines the Six Sigma methodology with another popular process improvement system known as lean. The lean method focuses heavily on streamlining processes and improving output by eliminating eight specific areas of waste: 

  1. Defects
  2. Overproduction
  3. Waiting
  4. Non-utilized talent
  5. Transportation
  6. Inventory
  7. Motion
  8. Extra-processing

Whereas the lean methodology focuses on improving process and output quality by stripping away all that is unnecessary and wasteful, Six Sigma seeks to eliminate root causes of errors to minimize the variability in repeatable processes. Combined, lean Six Sigma is a powerful system for cutting costs while improving the speed and quality of processes and production. 

Why Six Sigma might not work for everyone

While it has proven to be useful for companies and organizations of all stripes, the Six Sigma methodology has failed to impress some in the quality improvement field, most notably quality expert Joseph Juran. Juran’s main criticism is that Six Sigma is nothing more than a “basic version of quality improvement” that brings nothing new to the discipline. In Juran’s view, Six Sigma has “adopted more flamboyant terms, like belts with different colors,” but ultimately contributed nothing original to quality improvement.

Six Sigma has also been faulted for focusing on small, incremental improvements instead of big, radical ones. Critics assert that the Six Sigma process doesn’t facilitate finding innovative new strategies and methods and relies too heavily on rigid statistical tools. Additionally, an article published in Fortune magazine stated that while Six Sigma was effective at its intended function, it was “narrowly designed to fix an existing process” and was not helpful in “coming up with new products or disruptive technologies.”

Did you know you can get a Six Sigma certificate?

After GE and Motorola both developed in-house Six Sigma certification programs, many organizations and businesses followed suit in the 1990s. Certification levels include Yellow Belt, Green Belt, Black Belt, and Master Black Belt. However, there is no standardized certification test or certifying body, and these certificates are offered by various professional associations and universities.

How to get Six Sigma training

If you are interested in Six Sigma training and certification, first check to see if your company or organization has an in-house program or a preferred training provider. Otherwise, you can find any number of Six Sigma certificate options and training courses online, including at

If you’d like to learn more about how Wrike can help you implement Six Sigma practices in your team or organization, get started with a free two-week trial today.

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