Recently, I thought of the real reason why it doesn’t work as well as it should: it fails to accomodate the lunatic fringe trend of the bell curve. Six Sigma is all about FORCING processes to conform to the peak of the bell curve, which is centered around an idea or process which has already been established. Life doesn’t work that way. In Nature, the lunatic fringe, the deformity, the offshoots are what make change (whether for good or bad), usually a little bit at a time. The result is that, over time, the bell curve of a species or behavior shifts to become centered over that ‘different’ focal point. Six Sigma leaves no place for the freak, the random event, or diversity to spread the events of daily life, and thus, new ideas which would possibly improve the future customer base (black swans). It is designed to avoid changes which aren’t already designed into the system. In political and philosophical decision making, this is the equivalent of making all decisions based upon urban living, with no consideration for where the resources come from that make the city possible in the first place, and thus, being completely surprised whenever something surprising happens outside of the structured environment.
Sensitive dependence on dependency conditions.

However, he did note that some of his PhD research was bastardized and incorporated into Six Sigma–for instance, see this paper.

His specific argument for implementing this process isn’t that it is really revolutionary: all of these steps, taken individually or in aggregate, are “duh” levels of obviousness: measure what the quality of your output is, and figure out sensitivies of various inputs to optimize where you want to concentrate your improvements.

However, although the steps are obvious, they don’t necessarily get implemented. The reason is, at least in part, that large organizations fragment responsibility among teams, so “common sense” steps like these can fall through the cracks, or be shuffled off as “somebody else’s problem.” Therefore, by creating a process that Management buys into and supports (which is unfortunately filled with jargon), it actually happens.