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CHAPTER 11 ANALYSIS CONCEPTS AND PRINCIPLES 279

FAST is not a panacea for the problems encountered in early requirements elici-
tation. But the team approach provides the benefits of many points of view, instan-
taneous discussion and refinement, and is a concrete step toward the development
of a specification.

11.2.3 Quality Function Deployment
Quality function deployment (QFD) is a quality management technique that translates
the needs of the customer into technical requirements for software. Originally devel-
oped in Japan and first used at the Kobe Shipyard of Mitsubishi Heavy Industries, Ltd.,
QFD defines in the early 1970s, QFD “concentrates on maximizing customer satisfaction from the
requirements in a way
that maximizes software engineering process [ZUL92].” To accomplish this, QFD emphasizes an
customer satisfaction. understanding of what is valuable to the customer and then deploys these values
throughout the engineering process. QFD identifies three types of requirements
[ZUL92]:
Normal requirements. The objectives and goals that are stated for a prod-
uct or system during meetings with the customer. If these requirements are
present, the customer is satisfied. Examples of normal requirements might be
Everyone wants to requested types of graphical displays, specific system functions, and defined
implement lots of levels of performance.
exciting requirements, Expected requirements. These requirements are implicit to the product or
but be careful. That’s
how “requirements system and may be so fundamental that the customer does not explicitly
creep” sets in. On the state them. Their absence will be a cause for significant dissatisfaction.
other hand, often the Examples of expected requirements are: ease of human/machine interaction,
exciting requirements overall operational correctness and reliability, and ease of software installa-
lead to a breakthrough tion.
product!
Exciting requirements. These features go beyond the customer’s expecta-
tions and prove to be very satisfying when present. For example, word pro-
cessing software is requested with standard features. The delivered product
contains a number of page layout capabilities that are quite pleasing and
unexpected.

In actuality, QFD spans the entire engineering process [AKA90]. However, many QFD
concepts are applicable to the requirements elicitation activity. We present an overview
of only these concepts (adapted for computer software) in the paragraphs that fol-
WebRef
low.
The QFD Institute is an In meetings with the customer, function deployment is used to determine the value
excellent source for
information: of each function that is required for the system. Information deployment identifies both
www.qfdi.org the data objects and events that the system must consume and produce. These are
tied to the functions. Finally, task deployment examines the behavior of the system or
product within the context of its environment. Value analysis is conducted to deter-
mine the relative priority of requirements determined during each of the three deploy-
ments.