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Lean vs. Lean Six Sigma vs. Six Sigma vs. Other Methods

Lean six sigma

Lean Six Sigma is a performance and process improvement method that, unsurprisingly, combines both the lean and the Six Sigma methodologies – but how exactly are they different?

In this post, we’ll learn about each method, its use cases, their drawbacks, benefits, and more.

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Lean vs. Lean Six Sigma vs. Six Sigma vs. Other Methods

Lean, Lean Six Sigma, and Six Sigma are all well-known process improvement methodologies that share a similar underlying philosophy.

Predictably, both lean and Six Sigma began as different methods and were later combined into the Lean Six Sigma approach. All three have their distinct emphases, strengths, and applications, so it is worth understanding those distinctions before using any one of them.

Here is a brief rundown of each:


Lean is a methodology aimed at continual improvement and waste reduction. 

The methodology originally began as the systematization of the processes being used by Toyota in the 1950s in post-WWII Japan. Its efficiency and effectiveness has since fueled its global spread across the world into many different disciplines, from entrepreneurship to product development.

Principles and ideas of this methodology center around:

  • Incremental change and continual improvement, or kaizen, in order to improve processes and products, as opposed to radical and rapid change
  • The reduction of waste and the maximization of efficiency
  • Maximizing customer value

Objectives such as these are achieved through a systematic application of five principles:

  • Understanding and defining customer value
  • Mapping the value streams
  • Creating flow by reducing waste and maximizing efficiency
  • Establish pull, or limiting inventory through just-in-time delivery 
  • Pursue perfection by embedding continual improvement into the culture

While lean most certainly has its benefits – and it can be applied in a wide range of business areas – there are other methods that take a different approach to process improvement. Six Sigma is one such example.

Six Sigma

Six Sigma began as a manufacturing methodology at Motorola, then was later adopted by other global manufacturers, such as GE and Honeywell. Like lean, it has since spread to other disciplines and can be used in a wide range of business processes to improve performance.

Six Sigma shares several core aims with lean, such as continual improvement and the aim to improve process efficiency, business performance, and product quality.

Unlike lean, however, Six Sigma’s primary focus is on the reduction of defects and variability in the manufacturing process. By reducing inefficiencies such as waiting, transportation, inventory, and non-utilization of talent, Six Sigma aims to reduce errors to the absolute minimum. 

The focus in this methodology tends to take a more quantitative approach to process improvement, through:

  • The maximization of stability in processes
  • Data-driven measurements and adjustments
  • Commitment at every level of the organization

Six Sigma also leverages two five-step project development methods, DMAIC and DMADV, which are designed for project improvements and new projects, respectively.

Lean Six Sigma

Lean Six Sigma combines both the lean and Six Sigma methodologies by focusing on:

  • Organizational culture change
  • Reduction of waste and defects
  • Continual improvement

According to this approach, waste and defects fall under the same category, and can include:

  • Defective products
  • Over-production of products
  • Delaying processes
  • Non-utilization of talent
  • Excessive use of transportation during manufacturing
  • Excess inventory
  • Unnecessary motion by people
  • Extra-processing, or unnecessary production work

Like Six Sigma, Lean Six Sigma uses the DMAIC framework as an umbrella to combine both the lean and Six Sigma principles. It also grades the expertise of its practitioners based on a system similar to that used in karate or judo – namely, expertise is graded by “belts,” such as black belt, green belt, and so forth.

Benefits of Lean Six Sigma

Clearly, each approach has its own unique emphasis and approach. As a result, each will deliver its own set of unique benefits.

Lean, for instance, specifically aims to reduce waste, improve efficiency, and maximize product quality. Six Sigma, on the other hand, focuses on defect reduction and product quality.

Ideally, though, the use of Lean Six Sigma will deliver benefits from both systems and it can be used to improve everything from the company culture to process efficiency to product adoption.


  • A method for continually and incrementally improving products, processes, and services
  • A framework that focuses on maximizing customer value and product quality
  • The reduction of both process waste and product defects
  • Improved agility and nimbleness
  • An organizational culture that is more attentive to and focused on quality and continual improvement
  • A method that can be applied across the organization, not just in one area or department

In short, Lean Six Sigma is a system that can be used to fundamentally alter and enhance the organization at a deep level. While this methodology may not be suited for everyone – and it is certainly not a cure-all for every business problem – it is one good choice for those who want to enhance their organizational culture, improve processes, increase employee productivity, and create better products.

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