What's the difference between 6 Sigma and Lean


I've heard a lot of buzz about Six Sigma and Lean and I’ve talked to a number of our Validation and Regulatory Compliance members who would like to know more about them.

What are they? How do they differ? Do you need a certificate to get a job? And how can I find out if one is right for me?

𝐖𝐡𝐚𝐭 𝐢𝐬 𝟔 𝐒𝐢𝐠𝐦𝐚?

Six Sigma is a set of tools and techniques, a management system, a process improvement methodology, and more.

The Six Sigma model represents an integrated approach to achieving the lowest possible defects in products and services while maximizing customer loyalty and market share.

There are also historical links between six sigma and lean manufacturing. Lean manufacturing focuses on eliminating waste (making things right the first time), whereas six sigma focuses on reducing variation in processes so that defects can be virtually eliminated.

Lean is a Philosophy

Six Sigma is a methodology. Lean focuses on getting rid of waste and improving processes, while Six Sigma seeks to improve quality and reduce variation in manufacturing processes.

Lean can be thought of as the "how" (what we do), while Six Sigma is the "why" (why we do it). Both focus on reducing waste and improving processes but six sigma uses statistical methods to measure performance and predict future outcomes, whereas lean relies more on physical evidence for improvements.

Both Lean and Six Sigma are about eliminating waste and increasing productivity, but they differ in how those goals are achieved: Lean uses improvement theory while Six Sigma uses scientific methodologies like hypothesis testing; control charts; ANOVA analysis etc..

Which is better? Six Sigma or Lean?

Both Six Sigma and Lean are quality improvement methodologies that have been around for decades. While they share some similarities, they are also very different.

Lean focuses on reducing waste in the manufacturing process. It has been around since the 1950s and was developed by Toyota as a way to make manufacturing more efficient.

The goal of Lean is to increase production while reducing costs, which comes from eliminating wasted materials, optimizing processes and streamlining communication between departments within an organization.

Six Sigma focuses on improving processes for better product quality and cost reduction in any industry where a product or service is being delivered by a process (e.g., manufacturing).

The goal is to achieve “six sigma” performance — which means fewer than 3 defects per million opportunities (DPMO) — through process improvement, effective deployment of resources (human or material), measurement systems that provide real-time feedback.

Real-time feedback is about results achieved compared with goals set out at the beginning of each project/phase in order to adjust course if necessary before moving forward again towards improved performance levels over time until six sigma has been attained across all aspects of operation within an organization's value chain(s) overseen by management responsible for overseeing those operations."

What are the Six Sigma belts and levels?

The Six Sigma Green Belt is the first step in the Six Sigma certification process. To become a Green Belt, you must pass a four-hour exam with a score of at least 70%.

The next level up is Black Belt, which requires five years of experience as a Green Belt and passing an eight-hour examination with a score of at least 80%.

Yellow Belts are often used to stand in for employees who may not yet have enough evidence to qualify for their own positions within an organization. They can also be used as temporary replacements for people who have recently graduated from training but have not completed their education or certification requirements yet.

Orange Belts are similar to Yellow Belts but require no prior experience before applying; however, they do require candidates complete training within six months after applying—and three months before starting work—to ensure they understand all aspects of Six Sigma before beginning any projects while under contract with their employer or client (if any).

Orange Belts should also be able to demonstrate proficiency equivalent to someone who has been working as an Orange Belt for three months prior so that this credential still maintains some value beyond simply providing access into otherwise restricted areas within organizations where only certain types/levels are allowed entry without prior approval by management personnel responsible for overseeing such areas' operations.

Who should get certified as a Six Sigma Green Belt?

The Green Belt certification is for individuals who want to improve their career, learn more about Six Sigma and how it can help improve a company's performance. It’s also a great starting point for those who want to pursue their Black Belt certification.

To become a Green Belt, you should have:

  • At least one year of experience in an operational role
  • A solid understanding of the basics of Lean, Six Sigma and continuous improvement principles

What is Six Sigma certification, how to get certified and how much does it cost?

Six Sigma is a rigorous, structured approach to quality management. It was originally developed by Motorola in 1986 and has since been adopted by many businesses worldwide. The International Association for Six Sigma Certification (IASSC) offers the only globally recognized Six Sigma certification program, which can take years to complete.

The IASSC offers three levels of certification: Associate Black Belt (ABB), Green Belt (GB) and Master Black Belt (MBB). The process for achieving each level requires passing an exam that tests your knowledge of different aspects of Six Sigma such as DMAIC methodology, statistical process control methods and more advanced topics like modeling techniques or measurement systems analysis (MSA).

The Best Six Sigma Certifications

How do I find a job as a Six Sigma Green Belt?

The job market for Six Sigma Green Belts is strong, but it’s a competitive field. You may have to do some networking and research to find an opening. Look on job boards (like LinkedIn), search LinkedIn groups and forums dedicated to your industry, check with the local community college or university, check out local companies in your area, look at the Chamber of Commerce website, etc.

You don't have to pay for the training.

If you're looking for a career in Six Sigma, there's good news: there is a lot of training that is free! You don't have to pay an arm and a leg for this certificate.

That said, it's still important that you take advantage of the opportunity to get certified. The training itself is free, but if you want your certification, it'll cost $500 per exam session or $300 per exam session with an advanced course.

You can also pay $1,000 for three years of continuous access to all exams (including those not currently offered) and other benefits like additional practice exams and access to study guides that will help prepare you for the test.


In conclusion, companies looking to improve their production processes may consider implementing a business methodology. An organization that integrates Lean or Six Sigma strategies into its operations can improve in the areas of efficiency, value and productivity.

If you or your company wants to implement methods to improve its processes, it can be helpful to know the differences between Lean and Six Sigma to determine which method best fits your needs. 

Key takeaways:

  • Both Lean and Six Sigma are methodologies created to improve operational efficiency.

  • Lean vs. Six Sigma differ in their approaches, as Lean factors in a human element while Six Sigma does not.

  • Combining Lean and Six Sigma is challenging but when done, it’s called Lean Six Sigma.

A variety of industries can benefit from Lean or Six Sigma. However, the flexibility of the Lean methodology may allow for an easier implementation across a wider variety of industries. The data-driven Six Sigma approach, meanwhile, is often most beneficial for industries that manufacture products as opposed to offering services.


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