Six Sigma–Towards a New Definition of Quality

In the book Six Sigma:  The Breakthrough Management Strategy Revolutionizing the World’s Top Corporations, by Mikel Harry, Ph.D., and Richard Schroeder, the first chapter asks the basic question of “Why Six Sigma?”, in other words, why are companies adopting Six Sigma.

Six Sigma is a tool for improving the quality of a product, service, or result.    However, the definition of quality under Six Sigma is somewhat expanded from the traditional definition.

Quality consisted of conformance to a certain standard, so if your product fell within certain specification limits, your product had an acceptable level of quality.

However, the expanded definition of quality used in Six Sigma includes three new categories:

  1. Economic worth
  2. Practical utility
  3. Availability

Each of these factors in a product make customers want to purchase them.

1.   Economic Worth

This means producing a high-quality good or service at the lowest possible cost.    There is a difference between quality and grade, where a Volkswagen is expected to not have the same luxury features as an Audi, but both vehicles are expected to not require a lot of repairs.    What Six Sigma does is it lowers the cost to the producer so that this lower cost can be passed on to the consumer.

2.   Practical Utility

Let me tell you a story of what happened when I worked in Mitsubishi Motors.   I was visiting the manufacturing facility near Nagoya when I was asked if I wanted to be taken on a test drive of the new version of their SUV, the Montero (called the Pajero in Japan).    As I was being whizzed around the test track, I noticed the interior of the car and looked at the various gauges and dials on the dashboard.   I saw one I wasn’t familiar with, and I asked the driver what it was.    “Atarashii desu” he said noncommittally (“it’s new”).   Well, yes, I guessed that much, but I pressed him by asking, “dono tame desu ka?” (what’s it for?). In an almost embarrassed voice, he said it was a “koudokei”, an “altimeter”.    I thought to myself, “an altimeter?  What the hell do we need an altimeter for in a car?”   For about five seconds, I thought to myself, “oh my God!   Mitsubishi Motors has invented a flying car!”   And then sanity intervened, I realized that was extremely unlikely.   But I was still curious.

After the test drive, I asked the driver if this was some feature that the customers had been yearning for.   I don’t know, maybe there are a lot of offroaders who would like to know how far up the mountain they’ve gone and want to know what their altitude is about sea level.    Finally, the driver fessed up by saying that one of the engineers used to work for Mitsubishi Heavy Industries, the division of Mitsubishi that makes aircraft, and thought that an altimeter would like “sugoi” (cool) on the dashboard.

This was a clear case of adding a functionality where there was no thought to category 2 above, that is, of practical utility.   I mean, if you see the altimeter falling rapidly, chances are that there will be visual clues that will make this redundant, like the scenery passing upward past your windshield as you are falling off of a cliff.    So it was a valuable lesson on how adding functionality may not necessarily mean adding quality, especially if that functionality is not something that customers are clamoring for.

To create quality in terms of a product or service, the company must match its technical requirements to the customers requirements, and then focus on creating quality processes that make a product easy to use, not just during the “honeymoon” period of its first use, but during the entire expected life cycle of the product.     These three elements of practical utility can be summed up with the familiar phrase “form, fit, and function”.    “Form” means that it is pleasing to the driver’s interior (i.e., his senses), “fit” means that the parts meld smoothly into the product as a whole, and “function” means that it fits with the driver’s exterior behavior (driving pattern, etc.).

3.  Availability

The principle of availability, and it applies not only to a new product, but a product during its entire life-cycle.   If your car needs repairs, you need to know that parts will be available when you need them.

The Six Sigma process shows how well products perform and how well services are delivered, and then it shows how companies can improve processes and therefore improve both of these aspects, as well as decreasing the number of defects that appear to the point where they are rare indeed.   This lowers the cost of reworking, inspection and repair and thus the cost of production.  This allows companies to offer those products for lower prices, thus gaining market share.

So increasing quality lowers costs and increases profits–that in a nutshell is why Six Sigma is adopted by more and more companies, and not just those in manufacturing.




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