Applying Quality Function Deployment

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Applying Quality Function Deployment
to Software Development
ISQFD99-Brazil Pre-conference Workshop 2
Professor Hisakazu Shindo Yamanashi University
(Japan) shindo_at_kki.yamanashi.ac.jp http//www.is.e
si.yamanashi.ac.jp/shindo/
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Abstract
QFD was proposed as a quality assurance
methodology in developing a new product. Later,
QFD has been introduced into various
industries such as manufacturing, construction,
service, software, etc. QFD applications to
software development have been basically carried
out in the similar manner as employed in other
fields. Usually QFD starts with making a quality
table consists of requirements for quality and
quality elements. In software development, work
of design said to be more important than that of
other fields because its quality is almost
determined by design itself.
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In order to effectively apply QFD to
software development, a new methodology is
required. So, we must focus our attention on a
design-oriented aspect of QFD. First, we
consider two approaches to problem
solving. Then, we re-recognize the significance
of QFD. Lastly, we propose a basic concept for
applying QFD to software development.
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Contents Two approaches to problem
solving Engineering and a two-dimensional
table Relevant topics An application of QFD to
software development
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Two approaches to problem solving
Analytic approach QC storyis a typical
one. Design-oriented approach QFD can
be considered as one of
design-oriented approaches.
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Analytic approach

past present
This is on the causality basis. The process of
asking Why many times leads to problem solving.
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A design-oriented approach
Satisfying a desire by realizing something to be
made. This is correspondent to work of design
itself.

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Needs of design-oriented approaches grow while
QA activity is shifting from down stream to up
stream of a product development cycle.
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Quality assurance has deeply related to design
work.
We cannot help thinking about what design
is. Design is drawing or outline from which
something may be made. Design is general
arrangement or planning. Design is
pattern. Design is purpose, intention, or mental
plan.
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Engineering drawing
(Engineering) drawing is the art of representing
objects, scenes, etc by lines, with a pencil,
chalk, etc.
Front-view
Side-view
It consists of three orthogonal views.
Everything shaped can be designed in this way.
Top-view
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Analogy between drawing and a table
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Why do we start QFD with grasping requirements
for quality?
?
We know this is an automobile. So we can express
requirements for quality with relative ease.
We dont know what it is. So we cannot express
our needs.
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What is the key factor in developing a new
product?
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Why do we need such a large quality table?
Applying QFD directly to a finished product, the
size of its quality table easily becomes
large. To reduce the size of the table, some
people apply QFD restrictedly to a subsystem or a
part of the product. However, it is a
contradiction because the subsystem or the part
is determined after the design process considerabl
y progresses.
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If we want to have a handy table for QFD, we
should make it well-structured by any means.
Note that any two items of column and row
are allowed to exchange respectively. This
operation never violates the content of the table.
So, we can reduce the complexity of the table by
positively using this operation.
Quantification method of type three can be
utilized.
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This is an example of a description about staff
and their expertise.
Staff A has expertise concerning SPC and PC
and TQM is shared by staff C, D, E, F, and G.
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Applying QM3 to the previous table, we can obtain
the following
The result indicates staff can be classified
into four groups.
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A new paradigm of applying QFD
Marketing Value Engineering Quality
Management Reliability Engineering
Establishing basic concept of the
product Extracting major problems to be
solved (Bottleneck engineering)
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Establishing basic concept of the
product Extracting major problems to be solved
(Bottleneck engineering)
Function
A B C D E
Quality Cost Reliability
Balancing
Balancing
Technological viewpoint, Experiences, Knowledge,
Tools
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An application of QFD to software development
(1)Extract requirement for function and relevant
data from various kinds of users
requirements. (2)Make a two dimensional table of
function and data. (3)Apply the QM3 to the
table to nearly decompose it. (4)Specify the
function and data of each subsystem or module and
their interfaces. (5) Extract requirements for
quality with respect to each subsystem and
compose necessary quality tables. (6) Compose a
quality table and determine the quality level of
each function. (7) Design database while taking
functions into consideration. (8) Design
algorithms necessary to realize function of
subsystem to the satisfactory degree. (9) Extract
test cases considering actual operating
environment.
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