What is Six Sigma?

Six Sigma’s usage for measurement standards goes back to Carl Friedrich Gauss, 1855, when the normal curve concept was introduced.

Also, the measurement standards using Six Sigma for product variation can be traced back to 1920, where a process requires correction. An American engineer, while working at Motorola, coined the term “Six Sigma” in 1986, and it is a federally registered trademark of Motorola. Various other measurement standards, such as Zero Defects, Cpk, etc., came on the scene much later.

When 99.99966% of opportunities to produce a part are statistically expected to be free of defects is a six-sigma process.

Six Sigma is a rigorous and disciplined methodology that uses data and statistical analysis to measure and improve a company’s operational performance, improve the capability of business processes by identifying and eliminating “defects” in manufacturing and service-related processes

Defect reduction, improvement in profits, employee morale, and quality of products or services increases the performances and decreases process variation.

Six Sigma can be Defined and Understood at Several Levels

Philosophy: Processes require inputs (x) and produce outputs(y). This perspective looks at the processes that can be defined, measured, analyzed, improved, and controlled. This control on the inputs and outputs is generally expressed as y = f(x).

Tools: To drive the process improvement, qualitative and quantitative techniques are used by the Six Sigma experts.

Tools like statistical process control, control charts, and process mapping.

Methodology: DMAIC defines the steps a Six Sigma practitioner is expected to follow, starting with identifying the problem and ending with the implementation of long-lasting solutions.

What is Lean Six Sigma (LSS)?

Lean drives out non-value-added processes and procedures by promoting work standardization and flow.

It applies anywhere variation and waste exist, and every employee should be involved.

 Integrating Lean Six Sigma

While Lean focuses mainly on the reduction of waste, Six Sigma concentrates on variation reduction.

Lean successfully accomplishes its goals by the usage of less technical tools such as kaizen, workplace organization, and visual controls. On the other hand, Six Sigma inclines more towards the use of statistical data analysis, design of experiments, and hypothesis testing.

What is Six Sigma Certification?

Six Sigma Certification Levels

These certifications are accredited with bodies like the American Society for Quality (ASQ)

The different levels are color-coded like a white, yellow, green, black, and master black belt

  • Six Sigma White Belt

Six Sigma White Belts are those professionals who have not undergone a formal certification program or an extended session. A single session with an overview of relevant methods and vocabulary for LSS shows workers at all levels of an organization how they contribute to efficient, reliable outcomes. The White Belts participate in various projects and tasks involving analytical thinking that are associated with quality management and waste reduction, using this basic knowledge.  

  • Six Sigma Yellow Belt

The Six Sigma Yellow Belt certification is designed mainly for those professionals who are new to the concept of Sig Sigma and who are have a small role, interest, or the need to develop foundational knowledge. Yellow belts can be entry-level employees who seek to improve their world or executive champions who require an overview of Six Sigma and DMAIC.

  • Six Sigma Green Belt

The Certified Six Sigma Green Belt operates in support of or under the supervision of a Six Sigma Black Belt, analyzes and solves quality problems, and is involved in quality improvement projects. A Green Belt is someone with at least three years of work experience who wants to demonstrate his or her knowledge of Six Sigma tools and processes.

  • Six Sigma Black Belt

A professional who has the ability to explain the philosophies and principles of Six Sigma along with the supporting tools and systems is considered a Six Sigma Black Belt. A certified black belt should be able to display team leadership, recognize team dynamics and assign team member roles and responsibilities. Black belts have a thorough understanding of all aspects of the DMAIC model in accordance with Six Sigma principles. They have basic knowledge of lean enterprise concepts, are able to identify non-value-added elements and activities, and are able to use specific tools.

  • Six Sigma Master Black Belt

A seasoned Black Belt with strong leadership and problem-solving skills can go on to become a Master Black Belt in LSS. This designation indicates that an expert takes a broad view of strategy throughout a business, coordinating teams across.

This is the highest level of Six Sigma achievement. At this level, a professional will shape strategy, develop key metrics, act as a consultant, and coach black belts and green belts.

  • Champion

A Champion is an upper-level manager who leads LSS strategy and deployment. Based on the objectives set by executive leadership, Champions ensure that all initiatives to lower waste and remove defects come together in alignment with a company’s needs for growth. Aided by Master Black Belts, these managers mentor the leaders involved in LSS implementation and track their progress.

What are the different Six Sigma Methodologies?


The DMAIC methodology is almost universally recognized and defined as comprising of the following five phases:

  1. Identify the goals of the project and customer (internal and external) requirements.
  2. Measure the process to determine current performance.
  3. Scrutinize and verify the original cause(s) of the defects.
  4. Improve the process by eliminating defect root causes.
  5. Control future process performance.
  • DFFS

DFSS is the acronym for “Design For Six Sigma.” The stages or steps of DFSS differ from the DMAIC methodology in the fact that DFSS is not universally renowned or distinct.

DFSS is used to design or re-design a product or service from the ground up. For a DFSS product or service, the expected process Sigma level is at least 4.5 (not more than roughly one defect per thousand opportunities), though it can be 6 Sigma or higher depending on the product. Achieving a low defect level from a product or service being launched implies that customer expectations and needs (CTQs) must be completely analyzed before a design can be implemented.


This is one of the popular “Design for Six Sigma” methodologies. The five phases of DMADV are defined as:

  1. Identify the goals of the project and customer (internal and external) requirements.
  2. Assess and find out the needs of the customer and its specifications; scale competitors and industry.
  3. Analyze the process options to meet the customer's needs.
  4. Design (detailed) the process to meet the customer's needs.
  5. Validate the design efficiency and its capacity to meet customer needs.
  • When to Use DMAIC

The DMAIC methodology should be used when a product or process is in existence in the company but is not meeting customer specifications or is not performing adequately.

  • When to Use DMADV

The DMADV methodology should be used when:

  • A product or process does not exist in the company, and one needs to be developed.
  • The existing product or process exists and has been optimized (using either DMAIC or not) and still does not meet the level of customer specification or Six Sigma level.

Common Mistake and Pitfalls

A Six Sigma execution that is well planned consequently provides a very rewarding experience and colossal benefits for the organization. On the flip side, however, a flawed deployment may lead to disappointing results – the failure of the entire deployment effort and/or a significant waste of time and resources. Following common mistakes and pitfalls, which, if not handled well, will derail a deployment effort. By recognizing these mistakes and working to avoid them, a team can stay on track.

  • Overall: Right Six Sigma project not selected
  • Define Phase: Lack of good problem definition
  • Measure Phase: Not validating the measurement system
  • Analyze Phase: Not validating the Root Cause with data
  • Improve Phase: Lack of innovative solutions
  • Control Phase: Lack of sustenance
  • Lack of commitment and strong involvement of senior management
  • Faulty deployment strategies
  • Too much focus on training and certification
  • Lack of combined Efforts

 Context and Applications

Though most people relate Six Sigma to manufacturing, the concept is applicable to every type of process in any industry. In all settings, organizations use Six Sigma to set up a management system that systematically identifies errors and provides methods for eliminating them.

Six Sigma methodology is used predominantly to get rid of defects and improve operational efficiency. It aims at reducing defects by reducing variations in set processes. By reducing variations in set processes, Six Sigma achieves defect reduction. Reduced defects ultimately lead to increased efficiency. At times, variations in the process do not lead to the identification of defects. In such cases, dependence on Six Sigma for better operational efficiency proves no good.

Six Sigma methodology, combined with the Lean approach, makes the identification of defects easier. Lean approach, along with Six Sigma methodology, aids in the identification of defects and makes the process easier. The process to be improved by the implementation must be broken down into two parts. The part which has defects relating to variation must be improved by Six Sigma, and those which have defects relating to waste must be improved by the Lean approach.

Another more prevalent approach to get the best of both Lean and Six Sigma methodology is the step-by-step implementation.

  • Lean
  • Kaizen
  • Theory of constraints (TOC)

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