First cousins have might share the same grandparents, but they have different journeys to see those grandparents.  

Similarly, Lean and Six Sigma both share an aim to eliminate waste and make projects more efficient, but the way to get there is different.  

A core of both Six Sigma and Lean is to ensure value to both the customer and the business.  

But Lean’s method scrutinises the workflow/process and ensures the least possible resources are used. Six Sigma strives for near perfection of a final product and has a strong focus on data driven analytics.  

Lean can be more universally applied to business, particularly smaller business, whereas because of the data input required, Six Sigma would be better suited to a medium or larger organisation or project.  

Clifford D’Cunha, director of business consultancy and training programs with Performance Improvement Methodologies Training and Consultancy (PIMTC), says: “they’re both focused on optimisation, efficiency and productivity gains and they’re both focused on improving business processes.” 

“So, there’s obviously a lot of commonality and that’s why we have the kind of decided that together they work well.” 

The name Six Sigma comes from a statistical terminology regarding the number of standard deviations (six sigma) from the mean. 

“It’s where you actually run a lot of analytics and testing to ensure that you only get six defects per million opportunities,” D’Cunha says.   

“To give you an example, if you’re manufacturing a million cars, in those million, you can only have three defects. That’s the very high standard to get up. And so that’s their focus and it’s all about variation.” 

Six Sigma has five main steps called DMEDI:  

1 Define 

Gather information and determine the project scope.  

2 Measure 

How will you measure/calculate progress and success?  

3 Explore 

The project manager determines how the team can meet product requirements and exceed them.  

4 Develop  

Put a detailed strategic plan in place and work to it.  

5 Improvement 

A full review of the project and the lessons learned for all stakeholders.  

With Six Sigma, you have defined goals and measurable data.  

This data helps you learn improvements for next time and can be hugely beneficial. However, it can be time consuming gathering the data.  

Some also find Six Sigma’s strive for perfection is exhausting, while others argue the overarching product perfection philosophy can lead to cost blowouts in a project.