Lean vs Six Sigma

Over the past 10 – 15 years there’s been sort of a VHS vs Beta battle going on between Lean and Six Sigma.  I’ve been in the fortunate position to evaluate the battle from both sides.  I learned lean from working at Toyota’s premier plant in Georgetown, KY producing Camry’s, Avalon’s and Sienna’s at the time.  Then later, I earned my Six Sigma black belt while working at Ford’s iconic heavy truck plant (KTP) in Louisville, KY producing the F-250 to 550 and the Excursion.

I’ve always viewed the two methodologies as compatible in that structured problem solving as part of kaizen, is a key component within a lean enterprise.  Some proponents of Six Sigma will argue that lean is too feel good, loosey goosey and lacks discipline.  On the contrary, Toyota might not wave the wave the scientific method flag but the majority of statistical methods taught during my Six Sigma training were used daily in the trenches at Toyota.

At one point, I was asked to teach a Green Belt class.  I received the training material and started to evaluate them.  Much to my surprise, the material was a close match to the PPS (Practical Problem Solving) course that I used to teach at Toyota.  The biggest difference was that Toyota removed a lot of the math jargon which they knew might intimidate people and focused on the process of using the tool, the data and what the output meant.  So if you are trying to impress someone with your high math skills, use a Cause and Effect Diagram or if you want to understand the potential relationships between your problem and its variables use a Fishbone Diagram.

The simplification of terminology alone lowers the water level and enables so many more on the team to be involved.  With more involved in taking ownership of their problems and solving them, you get better solutions, more buy-in and long term sustainability.  If you want an elitist class structure of experts, then by all means, keep talking about regression analysis and R-squared values.  Or you can get everyone involved and talk about what has the greatest impact on the problem and what should be fixed first.

Currently, movements have resulted in a convergence of Lean and Six Sigma.  Typically, these movements have Lean as the over arching cultural methodology with the discipline of Six Sigma as the backbone of the problem solving system.  I think this is a good approach so long as the roll out doesn’t result in a class system.