Why Six Sigma with an emphasis on Lean
& the Theory of Constraints?

The classes I've attended—first, to learn as much as I can about Six Sigma, and later as an update to keep current as a Master Black Belt—have helped me become aware of a few of its shortcomings. Six Sigma emphasizes selecting a project that provides the greatest financial returns or the greatest savings to a firm. It also suggests selecting a financial person on your team to ratify all of these savings.  Well, I have learned over the years that the true savings in most projects initiated are unknown and unknowable (Deming). Second, the greatest savings can be a series of many smaller improvement events; they do not have to be major events.

The Theory of Constraints (TOC), properly defined as the Thinking Process (TP), addresses proper financial measurements and a different set of operational tools and measurements. Without this basis, it is practically impossible to evaluate the worth of any project’s returns. TOC helps us with proper operation measurements and the use of capacity and excess capacity that Six Sigma lacks. TOC also focuses us on the major weakness in the system or constraint. 

Using our present absorption accounting measuring tools could lead us completely astray.
Over the years, I have learned that most improvement initiatives taken that cost money, do
not contribute to a firm's bottom line. In fact they do just the opposite! TOC also provides
some tools totally independent of present-day Six Sigma measurements.

Lean or Kaizen-Lean allows us to attack small and short-term projects in our continuous
efforts to improve. We need to first understand Muda or all waste and prioritize and attack
these improvement efforts in isolation without having to establish each activity as a major
project. The emphasis is always for us to be system oriented and know what results we
expect before initiating any activities in isolation.

Six Sigma provides a great format for projects. Lean allows us to work on those projects
while continuously improving. TOC provides a new set of tools, proper measuring, and the
directional focus that Six Sigma and Lean need for the fastest rate of really measurable
improvements.