Six Sigma vs. Lean Six Sigma

For those becoming acquainted with Six Sigma and Lean Six Sigma, a frequent question is:

What is the real difference between Six Sigma and Lean Six Sigma?

The short answer is that the two methodologies complement one another. However, differences exist between them. When looking at Six Sigma vs. Lean Six Sigma, it’s important to understand the goals and tools used by both.

What is Six Sigma?

Six Sigma is a process improvement methodology that focuses on eliminating defects. The goal is to have only 3.4 defects per one million opportunities in any process.

Motorola first began using the methodology in its manufacturing plants in the 1980s. The data-driven process helped the company earn record profits.

Two main tools are used in Six Sigma: DMAIC and DMADV.


Standing for define, measure, analyze, improve, control, DMAIC is used to improve existing processes that do not meet an organization’s standards for limited defects and overall efficiency. It works as follows:

  • Define the nature of a process defect, as well as the goal for the process
  • Measure every aspect of the process using data from current operations
  • Analyze to find root causes that are leading to the defect
  • Improve the process using this information and eliminate the defect
  • Control the process to maintain and sustain improvements


This focuses on steps used to create a process that results in a new product or service. The acronym stands for define, measure, analyze, design, verify. It works as follows:

  • Define the process goal
  • Measure every aspect of the proposed new process
  • Analyze the data to create options for the process, eventually choosing the best one
  • Design the new process and test its efficiency and quality
  • Verify the design through pilot projects before the final process is initiated

The overall goal of Six Sigma is to eliminate defects. Too many defects lead to inferior products and services. It also erodes consumer confidence in a product.

What is Lean?

While Six Sigma focuses on eliminating defects, Lean Six Sigma focuses on bringing value to customers. Every aspect of an operation is analyzed through this lens.

Lean also focuses on moving quickly with process improvement, sustaining what works and changing what doesn’t work.

Lean operates under five main principles.

  • Evaluate every process from the view of whether it provides value to the customer
  • Identify every step in a process and eliminate those that don’t add value
  • Create a schedule so that the value-adding activities work smoothly together and within a specified timeframe
  • Incorporate feedback from customers that adds further value
  • Focus on continuous improvement to the process, moving it closer to perfection over time with all wasteful activity eliminated

The Eight Wastes

The most important aspect of Lean is identifying waste. Lean organizes wasteful activities into eight categories:

  • Defects: Process errors
  • Over-Production: Having more product than needed or producing it before it is needed.
  • Waiting: Time wasted waiting for the next process step
  • Non-Utilized Talent: Not properly using employee’s knowledge and skills
  • Transportation: Unnecessary movement of products and materials
  • Inventory: Having products or materials that are going unused
  • Motion: Unnecessary movements by workers
  • Extra-Processing: Providing a higher standard or larger amount of work than necessary

Lean Six Sigma vs. Six Sigma

Lean and Six Sigma work best when combined, which is why Lean Six Sigma was created.

Lean focuses on creating processes and governing all operations from the standpoint of whether all activities benefit the customer. Six Sigma takes a process and analyzes it to create the most efficient and waste-free operation possible.

Used in tandem, they offer a powerful force. While Six Sigma started in manufacturing, it now is applied to many different operations in a variety of industries, including healthcare, software development, pharmaceutical, manufacturing, nonprofit agencies and government agencies.

Lean has the same track record. With its emphasis on working fast and always focusing on the customer, it has especially taken hold in technology. But it works well across every industry, as well.

Mastery Levels of Lean Six Sigma

Those interested in Six Sigma and Lean should consider the benefits of earning certification in Lean Six Sigma methodology.

The levels of certification in Lean Six Sigma are White, Yellow, Green, Black and Master Black Belt.  White and Yellow provide basic training in the language and strategies involved in Six Sigma. Green Belts typically work as assistants on projects with Black Belts, who act as project leaders.

Master Black Belts have attained mastery over Six Sigma methods and gained the experience of leading many successful projects. They typically work on Six Sigma projects full-time and play a key role in improving an organization’s operations, working directly with top executives.

While differences exist between Six Sigma and Lean, the two work toward the same goals of increased efficiency and better products. Learning the methodology can put an employee in a great position to move into key management roles within an organization.

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