What are the Differences Between Six Sigma, Lean and Lean Six Sigma?

If you’re considering obtaining a quality improvement certification, you may have heard the terms Six Sigma, Lean methodology or Lean Six Sigma.  If you’re wondering if there is a difference between Six Sigma and Lean, if one methodology is better than the other, or what exactly Lean Six Sigma is, read on.

Defining and explaining Six Sigma, Lean, and Lean Six Sigma is essential to answering these questions. Understanding their basic definitions, and what purpose each serves, helps us know when to use one methodology over another, or implement a hybrid methodology, in a particular situation.

What is Six Sigma?

Six Sigma concentrates on improving the quality of goods or services an organization produces by reducing variance in the production process. Variance is the enemy of Six Sigma. When a production process lacks the stability to consistently create high-quality output, it will continue producing defective products until professionals intervene and improve the process.

How does Six Sigma define high quality? A production process that produces 3.4 defects per one million opportunities is acceptable by Six Sigma standards.

Those who improve the inconsistent production processes are critical to success. Six Sigma gives these individuals belt rankings, much like martial arts, depending on their level of training and expertise. Individuals of various belt rankings make up project teams that use a system of defining, measuring, analyzing, improving and controlling (DMAIC). Applying DMAIC to an inconsistent process can decrease variance and increase the quality of goods or services.

What is Lean Manufacturing?

The enemy of Lean manufacturing is waste. Waste is defined as any activity that consumes resources without adding value. Waste may take the form of unnecessary transportation, idle inventory or wasted motion, but it all acts to make the production process less efficient and more prone to producing defective outputs.

Lean focuses on the big picture and seeks to eliminate waste along the entire value stream, not just at isolated points of production. Lean is not just about improving quality. It seeks to create an organizational culture dedicated to continuous improvement, employee empowerment and elimination of waste.

Organizations that adopt a Lean philosophy not only make production improvements, but also reap the accompanying benefits of improvements in cost, quality and service.

What is Lean Six Sigma?

As its name implies, elements of Six Sigma and Lean quality improvement methodologies are combined to create Lean Six Sigma. Quality improvement advocates quickly realized that they could solve a greater number of problems by creating a quality improvement hybrid that employs the best of both worlds.

In practice, Lean Six Sigma uses Lean methodologies and tools to identify and remove waste. It also employs the DMAIC cycle from Six Sigma to eliminate waste(s) in the process.

Which Method Should You Use?

Quality improvement novices sometimes ask, “Which is the best method?” This is the wrong question, as it implies one method is superior in all circumstances.

A better question to ask would be, “What method or combination of methods would the process respond to best?”

In this scenario, you are not locked into a rigid application of Six Sigma, Lean methodology or even Lean Six Sigma. The approaches can be mixed and matched as individual situations require, but these important decisions shouldn’t be made by the novice.

To find out more about Six Sigma training and what Villanova University has to offer, visit our Six Sigma certificate page.