Page 24 - Design for Six Sigma a Roadmap for Product Development

2 Chapter One

expected service levels are different. When a product or service sur-
passes our expectations, we consider that its quality is good. Thus,
quality is related to perception. Mathematically, quality can be quan-
tified as follows:
P
Q (1.1)
E
where Q quality
P performance
E expectations

The perceived “performance” is actually “what this product can do for
me” in the eyes of customers. The American Society for Quality (ASQ)
defines quality as “A subjective term for which each person has his or her
own definition. In technical usage, quality can have two meanings: 1. the
characteristics of a product or service that bear on its ability to satisfy
stated or implied needs. 2. a product or service free of deficiencies.”
By examining the ASQ’s quality definition, we can find that “on its
ability to satisfy stated or implied needs” means that the product or
service should be able to deliver potential customers’ needs; we call it
“doing the right things,” and “free of deficiencies” means that the prod-
uct or service can deliver customers’ needs consistently. We can call
this “Doing things right all the time.”
However, when we try to further define “what is quality” in detail,
we would easily find that quality is also an intangible, complicated
concept. For different products or services, or different aspects thereof—
for different people, such as producers, designers, management, and
customers, even for different quality gurus—the perceived concepts of
quality are quite different.
According to David A. Garvin (1988), quality has nine dimensions.
Table 1.1 shows these nine dimensions of quality with their meanings
and explanations in terms of a slide projector.
There are also many other comments about quality (ASQ Website:
www.asq.org):
■ Quality is “wow”!
■ Quality is not a program; it is an approach to business.
■ Quality is a collection of powerful tools and concepts that have proved
to work.
■ Quality is defined by customers through their satisfaction.
■ Quality includes continuous improvement and breakthrough events.
■ Quality tools and techniques are applicable in every aspect of the
business.