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What is Six Sigma and is Six Sigma Still Relevant?

Written by: Michael Rapaport

What is Six Sigma and is Six Sigma Still Relevant?

Critics have questioned the wisdom of relying too heavily on Six Sigma, like so many other quality management buzz phrases, in today's global manufacturing industry. If you are a strong advocate for Six Sigma-based continuous improvement processes, you should already be familiar with such backlash. Maybe, your company tried to implement Six Sigma and utterly failed, which might place you firmly in the skeptic category? This blog post opens the debate over Six Sigma once again, posing the questions: What is Six Sigma and is Six Sigma still relevant today? The answer may surprise you.

A brief history of Six Sigma

Since the 1980's, Six Sigma has been used by manufacturers to come as close as possible to the zero-defect ideal. Viewed from a high level, the overarching premise of Six Sigma is to utilize the DMAIC (define, measure, analyze, improve and control) cycle to eliminate process variation, thus reducing product defects by ensuring processes are consistent and predictable - leading to substantial cost of quality reductions for many manufacturers. In more than a few high-profile cases, companies have realized savings in the range of billions of dollars. If you are familiar with statistics, "sigma" is a term that refers to standard deviations, which in a manufacturing context correlates to deviations of a particular process out of specification. Six Sigma is the buzz phrase coined during the 1980's by companies that realized major cost reductions by seeking to achieve "six sigmas" between the statistical mean of a process and the closest specification limits. By adopting the DMAIC cycle in tandem with a data-driven approach to identifying "defects" in processes, you can use Six Sigma's continuous improvement methodology to come as close as possible to the zero-defect ideal.  More about several manufacturing statistics Statistically speaking, a Six-Sigma level of quality should theoretically achieve 99.9997% yield and equate to 3.4 defects per million opportunities. If these numbers make you raise an eyebrow and wonder precisely where these figures come from, you are not alone in your skepticism. Without delving into the intricacies behind the mathematics too deeply, Six Sigma statistical methods hinge on a standard deviation of plus/minus 1.5, the "Six-Sigma shift." As such, the fundamental veracity of its statistical presumptions has been questioned time and time again.

Three criticisms of Six Sigma today

As you would expect of any other manufacturing buzz phrase, the term Six Sigma has been re-branded under the guise of Lean Six Sigma, which not surprisingly claims to address the shortcomings of "lean manufacturing" and Six Sigma, allegedly ensuring the best of both worlds of course. The debate on whether or not Six Sigma is even fundamentally viable could go on ad infinitum, but three criticisms of it surface again and again:

  • Six Sigma as a one-dimensional philosophy
  • Six Sigma as a short-sighted business approach
  • Six Sigma as an outsourced service.

The first criticism claims that Six Sigma focuses on cost reductions too narrowly and not every quality management woe can be distilled to cost of quality metrics. Secondly, it does indeed yield cost reductions over the short term, but many cases abound where Six Sigma initiatives started promising before abruptly running into the proverbial wall. Lastly, Six Sigma knowledge has been viewed as an outsourced, arcane discipline where high-paid consultants rule the day, certified as Black Belts, or Master Black Belts if you have a particularly troublesome process. More Quality Buzz Words Defined

Is Six Sigma still relevant?

Yes, Six Sigma is still relevant today because this methodology has become standard issue for any new manufacturer (or quality manager) hoping to gain credibility as a high-quality business partner. Its continuous improvement philosophy aligns with ISO 9001 standards well, but context is the missing variable in Six Sigma. In short, Six Sigma is not applicable to every quality management issue. What you need to keep in mind when discussing the pros and cons of Six Sigma is a holistic approach to quality. Since Six Sigma is a data-driven methodology, you need to be able to tame the data deluge currently inundating your IT capabilities. "Garbage in, garbage out" is a time-tested buzz phrase, but "garbage in, gospel out" is an even better analogy for the state of Six Sigma today. Despite its widespread adoption, you should not be afraid to stand up and challenge Six Sigma if you find data that contradicts its output. 5 Ways You Need to Be Using Quality Management Analytics Today. When it comes to Six Sigma, every quality management professional has an opinion to share. Your view on it may be positive or negative, but one aspect of this debate is certain. Six Sigma is still relevant when placed in context with sound data and holistic quality management processes.