What is Six Sigma?

Six Sigma is a very robust method that can be applied to process optimization in production, service and administrative companies. As a process optimization method, it increases customer satisfaction and improves a company’s bottom line by reducing variation, errors, cuts and rework.

It is a method that has proven very effective for solving complicated quality problems, but also for preventing errors and maintaining control of processes.


You can use the method to: 1) Improve existing products, processes and services using the DMAIC project model, and 2) Develop world-class products, processes and services using Design for Six Sigma (DFSS).


What is a Six Sigma DMAIC project?

Most Six Sigma projects are implemented with the DMAIC project model, which is used to improve existing processes, products and services. It is a 5-phase project model:


Define     What is the problem?

Measure  How big is the problem?

Analyze   What cause the problem?

Improve   Which solution(s) remedy the cause(s)?

Control    To what extent is the problem solved?



Firstly, the business case is determined and management’s priorities are understood. Then the process is described in depth in 5 to 7 process steps, customers are identified and the customers’ expectations are specified.



We will investigate how the process performs in terms of customer expectations. These results will be used as the baseline from which the scale of improvements can be accurately measured. At the same time, we ensure that data is accurate and reliable through a measurement system analysis (MSA). We develop a data collection plan in order to identify the underlying causes of challenges that can be improved.



The collected data is analyzed and the main underlying causes are identified and quantified. Once a satisfactory amount of the problem at hand can be explained from the underlying causes, the project can move on to the next phase.



Here, we develop and implement the solutions needed to improve the process.



It is crucial that the improvements in results are maintained and developed further. Therefore, in the final phase, a monitoring plan is implemented to ensure that the performance of the improved process is retained.


When is Six Sigma relevant?

It makes sense to use Six Sigma when a commonsense approach has not solved a problem, e.g., after using an A3, in conjunction with an 8D report.

That’s when:

  • Quality challenges are complex
  • A problem continues to arise
  • There is too much variation in quality and/or delivery


Six Sigma as a project model

Six Sigma can be used as a project model for process optimization by a trained Six Sigma Green Belt or Six Sigma Black Belt person.


Six Sigma as a quality management strategy

The Six Sigma method can also be implemented as a true quality management strategy. When it is applied this way, organizations can reap the greatest benefits.


What are Six Sigma belts?

The Six Sigma belts signal a trained person’s level of competence within Six Sigma.

Six Sigma White Belt    A person who has been introduced to the method for ½-1 day.

Six Sigma Yellow Belt   A person who has been introduced to the method for between 2 and 5 days.

Six Sigma Green Belt    A person who has the skills to lead improvement projects within his or her department or own field of study. Green Belts often spend up to 25% of their work time in this role.

Six Sigma Black Belt      Black Belts are normally a 100% dedicated resource who can carry out complex and interorganizational projects.

Master Black Belt         There are two archetypal profiles: 1) The specialist who shows great professionalism in implementing Six Sigma projects and 2) The organizational leader who acts as part of the management structure, with focus on organizational implementation and operation.


What is Six Sigma certification?

There is no single certification organization, and no single entity has a trademark on the Six Sigma method. Therefore, you may find that there are big differences in what Six Sigma-qualified individuals can actually do. There are a number of organizations that offer certification, and many major international companies also have their own internal certification.


Examination and certification

A Six Sigma certification consists of both an examination of theoretical knowledge and a certification based on a practical improvement project, where significant improvements can be shown.


Real Six Sigma competencies

If you want to make sure that a Six Sigma-qualified individual has real competencies, you must enquire about the results they have achieved using the method.


3 pillars of Six Sigma

There are three pillars that make the Six Sigma method effective for process optimization and quality improvements.



It is the customers who define the quality as they are the people who ultimately approve or reject your product/services. Therefore, it is crucial to understand the customer’s most important requirements so that there is consensus from the beginning. Doing so also allows you to recognize when events have occurred either within or outside of a customer’s requirements.



All work processes can be considered as processes with one or more inputs, each having one or more suppliers. A process also has one or more outputs with one or more customers (recipients) with output requirements.

The output (y) is always a function of an input and processing in the process (x). This causal link is central to the method and in process optimization. This is most often expressed as Y = f (x).



The method largely utilizes data and ensures that the data is accurate and reliable. It ensures a high level of professionalism, but also that decisions and improvements are rooted in facts.


Management Anchored & Change Management

In addition to the three pillars, the Sigma Six method ensures that management support is in place, because no Six Sigma projects are launched without management commitment.

The change management occurs naturally because each member of the project team represents a sub-process of the process that is being optimized. They contribute with knowledge about the process and the potential causes of problems, and subsequently succeed in finding solutions as they are the individuals who will continue to work in the improved process after said solutions have been implemented. This gives them a completely natural ownership of the solution and improvement.


Six Sigma tools for process optimization

There are many good quality tools and methods in the Six Sigma toolbox. They can all be applied individually to different quality issues.


  • SIPOC, Supplier, Input, Process, Output & Customer
  • COPQ, Cost of Poor Quality
  • CTQ, Critical To Quality
  • Kano model (used to analyze customer requirements)
  • Pareto chart
  • Histogram
  • MSA, Measurement System Analysis
  • FMEA, Failure Mode and Effect Analysis
  • D-FMEA
  • P-FMEA
  • SPC, Statistical Process Control and Control Cards
  • Fishbone diagram / Ishikawa
  • Process mapping, e.g. swimlane diagram, flow chart, spaghetti charts, etc.
  • DOE, Design of Experiments
  • A large number of hypothesis tests
    Brainstorming methods
  • Priority and selection methods
  • Cost benefit analyzes
  • Poke Yoke


More than 15 years of practical experience

At eye4improve, we have more than 15 years of practical experience working with the Six Sigma method to solve quality issues and improve process performance.


We have successfully helped many companies improve their processes and solve their quality issues. We are ready to help you, so you can enjoy a high level of customer satisfaction and at the same time improve your bottom line. Read more about our work here..