Common Misconceptions about Six Sigma

Our online Green Belt program includes an assignment where students are introduced to Six Sigma by reading a lecture, reading Chapter One in the text, and viewing several videos.  They are then challenged to explain how the readings and videos either reinforced or changed their preconceived notion of what Six Sigma is, based on what they knew prior to starting the course.  After reviewing hundreds of submissions for this assignment, the following misconceptions are common.

Thinking that Six Sigma is applicable only in manufacturing is a very common misconception.  Six Sigma does have its roots in manufacturing, but is now widely used in law, non-profits, retailing, sales and marketing, health care, finance, IT, the military and many other fields.

Many students think that Six Sigma is only focused on internal operations and express surprise that Six Sigma has an outward customer focus.  To me that is the most natural way to do business!  Without satisfied customers no business has any hope of being successful.  I also point out that customers may be external to the organization or internal.  We should always think of the next person or next operation in the process as a customer.

A common misconception is that it costs more and more money to improve quality as quality levels approach perfection.  As Motorola matured in the application of Six Sigma, the company continued to pursue quality improvement to levels that were far beyond what customers were asking for.  They did so because they found that as quality levels approached perfection, the cost of operations continued to drop.  It is a fallacy that you need to spend more to achieve excellent quality, or that there is some point at which quality improvement is not cost effective.  In fact, you continue to save money as more problems are eliminated.  You also gain in customer satisfaction.  I great read on this subject is the book “Quality Is Free” by Phil Crosby.

Students often perceive Six Sigma as being entirely about the use of statistics prior to starting the course.  The use of data and statistics is a part of the Six Sigma methodology but is far from the be all and end all of Six Sigma.  Six Sigma is a fact and data based problem solving approach that uses a variety of tools and techniques ranging well beyond just statistics.

Many students think that Six Sigma is “all new” and are surprised to learn that the tools and techniques have been evolving for well over a century.  In our Black Belt course, students read about many of the pioneers in the quality field such as Shewhart, Juran, Deming, Taguchi, Ishikawa and others, and then construct a timeline of how they influenced each other.  Here are some examples:

  • 1896 – Vilfredo Pareto published a paper identifying the Pareto principle.
  • 1902 – Toyota Production System evolution began with the concept of Jidoka.
  • 1918 – Sir Ronald Fisher developed Analysis of Variance, followed by Design of Experiments.
  • 1924 – Walter Shewhart developed control charts.
  • 1950 – Gen’ichi Taguchi articulated target values and robust design principles.
  • 1968 – Kaoru Ishikawa developed the cause and effect diagram.
  • 1979 – Phillip Crosby popularized the concept of the cost of quality.

Students often begin the course thinking that the goal of Six Sigma is to hit some arbitrary level of quality.  The goal is in fact to reduce cost and improve customer satisfaction by improving quality to as close to perfection as possible.

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About the author:  Mr. Roger C. Ellis is an industrial engineer by training and profession.  He is a Six Sigma Master Black Belt with over 50 years of business experience in a wide range of fields.  Mr. Ellis develops and instructs Six Sigma professional certification courses for Key Performance LLC.   For a more detailed biography, please refer to