Comparing Lean and Six Sigma and the Impact of Theory of Constraints

Comparing the Impact when Lean and Six Sigma are Implemented stand-alone, versus in combination with Theory of Constraints

The Theory of Constraints/Lean “either/or” decision you do not need to make

A California Corporation conducted a 2-year experiment over 21 plants – 11 plants applied Six Sigma, 4 plants applied Lean, 6 plants applied TOC AND applied Lean and Six Sigma within the TOC improvement framework.

Among the key measurements they used was “contribution to financial savings” … not an ideal measurement from a Theory of Constraints perspective where the focus is typically on making more money rather than saving money (although reduction in Operating Expense is a common side-effect of a TOC implementation that we’re always happy to see, of course). The measurement is more in line with Lean and Six Sigma.

But even with measurements more commonly associated with Lean and Six Sigma, what were the results?

  • 89% of total cost savings came from the 6 plants using the TOC approach.

  • 7% of total cost savings came from the 11 plants using Six Sigma alone.

  • 4% of total cost savings came from the 4 plants using Lean alone.

You can download this report from the link below:

Published Report of the Experiment

TOC does NOT push Lean or Six Sigma aside. Rather, it focuses their contribution for maximum competitive and profit advantage.

This article makes the point, emphatically.