Page 132 - Design for Six Sigma for Service (Six SIGMA Operational Methods)

Quality Function Deployment 107

people, it cannot be acted upon directly. Legal and safety requirements or
other internal wants are considered extensions to the Whats. The Whats can
be characterized using the Kano model (Sec. 6.5).

Hows
Hows are design features derived by the DFSS team to answer the Whats. Each
of the initial Whats needs operational definitions. The objective is to determine
a set of CTS requirements with which Whats can be materialized. The
answering activity translates customer expectations into design criteria such as
speed, torque, and time to delivery. For each What, there should be one or more
Hows that describe a means of attaining customer satisfaction. For example, a
“cool car” can be achieved through a stylish body (different and new), seat
design, leg room, lower noise, harshness, and vibration requirements. At this
stage only overall requirements that can be measured and controlled need to be
determined. These substitute for the customer needs and expectations and are
traditionally known as substitute quality characteristics. In this book, we will
adopt the critical-to terminology aligning with Six Sigma.

Teams should define the Hows in a solution-neutral environment and not be
restricted by listing specific parts and processes. Just itemize the means (the
Hows) whereby the list of Whats can be realized. One-to-one relationships
do not usually exist in the real world, and many Hows will relate to many
customer wants. In addition, each How will have some direction of
goodness or improvement as illustrated in the following figure:

Direction of improvement
Maximize 1.0
Target 0.0
Minimize −1.0
The circle represents the nominal-the-best target case.

Relationship Matrix

The process of relating Whats to Hows often becomes complicated by the
absence of one-to-one relationships as some of the Hows affect more than
one What. In many cases, they adversely affect one another. Hows that could
have an adverse effect on another customer want are important. For
example, “cool” and “stylish” are two of the Whats that a customer would
want in a vehicle. The Hows that support the “cool” attribute are lower
noise, roominess, and seat design requirements among others. These Hows
will also have some effect on the “stylish” attribute as well. A relationship
is created in the house of quality (HOQ) between the Hows as columns