Introduction
In my past entries, I jumped in immediately in posting JMP scripts that are useful for SPC practitioners. I have not spent much time though in introducing, defining, and explaining what SPC is. Allow me to back step this time. In this entry I would take time to look at the basic concepts in detail, and there is no better jumping board than the Definition of Quality.
Definition of Quality
About 8 years ago I was already visualizing myself pursuing a career in Quality Management. I was daydreaming of solving very complex problems, deploying quality management systems, initiating customer-focused activities, and all other things that could convince even the hardest person that I am the God’s gift to the Quality Community. But then my professor in Statistical Process Control course came in our classroom and threw a question to start a discussion. After a long pause made by waiting for someone to answer, the professor looked at me and asked, “How about you Rey, how would you define Quality? What is Quality for you?” I was dumbfounded of course. Not only because I know I can not give a satisfactory answer, but more of the realization that I was dreaming big while not even knowing what it is I was dreaming about. How could I manage Quality if I can not even define what Quality is in the first place? Well I gave the professor a reply, “Quality is consistently exceeding the expectations”, but after that my mind wandered-off for the rest of the class. I have learned that very moment that I do not know enough. Actually I learned that I really do not know a thing about Quality, and that lesson is enough for me for one day.
After that incident I decided to do some personal research. Here is what I recall of what I came up with.
“Quality is Fitness of Use” – Joseph M. Juran
Joseph Juran is the chief editor of The Quality Handbook (1999) and is the person behind the Pareto Concept (Vital Few, Trivial Many). Juran defines quality as fitness of use. According to him, quality is the freedom from deficiencies. Quality from his point of view therefore costs less, since this implies fewer defects and less scrap rates. It also means gain in productivity brought about by decreasing reworks, and increase in customer satisfaction made by products or services that are free from flaws.
“Quality is Conformance to Requirements” – Philip B. Crosby
Philip Crosby is credited for popularizing the concepts Zero Defect and Quality is Free. According to Crosby quality is the conformance to the requirements, and therefore does not cost any. What adds cost is not doing it right the first time. This additional cost he termed as the Cost of Poor Quality. Crosby shares with Juran the concept that quality actually costs less. They differ however on the perspective of how the end product is used. For Juran, it is the customer who ultimately decides if the end product or service is of quality. For Crosby however, it is the conformance to the specifications or written procedures that defines the quality. The question of whether that specification is “fit for use” is irrelevant. As long as the requirement is met, quality is present.
An important note must be made at this point. A Quality Practitioner should be able to distinguish between Juran's and Crosby’s concepts. It should be clear that they are referring to two different aspects of quality. One is the Quality of Design, while the other is the Quality of Conformance. A product may have been able to meet the design requirements but if the design itself is poor the product may end up as unfit for use. On the other hand it is also possible to have a superb design, but when an end product can not conform to its specifications quality is not present either.
“Quality is How the Customers Define it” – W. Edwards Deming
Edwards Deming is the person behind the well known Plan-Do-Check-Act Cycle. His advocacy on Quality is that only the customers can define it, and it typically changes from time to time. Focus therefore should be on understanding the customer, translating their needs and wants into measurable quality characteristics, and continuously reducing product variations in terms of these characteristics. For Deming, quality increases as the variation decreases. From this perspective, Quality does not necessarily mean less cost. Since quality from this definition may mean meeting customer wants, improving process performances, and tightening of tolerances, then quality may actually cost more.
“Quality has 8 Dimensions” – David A. Garvin
David Garvin is a Harvard Professor famous for his development of the 8 Dimensions of Quality concept. According to Garvin quality is multi-faceted and has 8 faces. These are the following:
1. Performance
2. Features
3. Reliability
4. Conformance
5. Durability
6. Serviceability
7. Aesthetics
8. Perceived Quality
--to be continued…
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