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Noted Quality expert Joseph Juran has criticized Six Sigma as "a basic version of quality improvement",
stating that "[t]here is nothing new there."
Studies that indicate negative effects caused by Six Sigma
A Fortune article stated that "of 58 large companies that have announced Six Sigma programs, 91
percent have trailed the S&P 500 since." The statement is attributed to "an analysis by Charles Holland
of consulting firm Qualpro (which espouses a competing quality-improvement process)." The gist of the
article is that Six Sigma is effective at what it is intended to do, but that it is "narrowly designed to fix an
existing process" and does not help in "coming up with new products or disruptive technologies." Many
of these claims have been argued as being in error or ill-informed.
A Business Week article says that James McNerney's introduction of Six Sigma at 3M may have had the
effect of stifling creativity. It cites two Wharton School professors who say that Six Sigma leads to
incremental innovation at the expense of blue-sky work.
Based on arbitrary standards
While 3.4 defects per million might work well for certain products/processes, it might not be ideal for
others. A pacemaker might need higher standards, for example, whereas a direct mail advertising
campaign might need lower ones. The basis and justification for choosing 6 as the number of standard
deviations is not clearly explained.
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