INTRODUCTION TO SOFTWARE DESIGN FOR SIX SIGMA (DFSS) - Software Design for Six-Sigma: A Roadmap for Excellence - page 185

services, and strategies that will more than satisfy their customers is a structured
approach. Defining customer needs or requirements and translating them into specific
plans to produce products to meet those needs are major QFD activities. It is effective
for focusing and aligning the project team very early in the identify phase of software
DFSS, identifying gaps and targets, and planning and organizing requirements at all
levels of the design. QFD can be used in all phases of DFSS (ICOV).
Survey analysis is a popular technique to collect VOC. This survey is used to gather
information from a sample of individuals, usually a fraction of the population being
studied. In a bona fide survey, the sample is scientifically chosen so that each person
in the population will have a measurable chance of being selected. Survey can be
conducted in various ways, including over the telephone, by mail, and in person. Focus
groups and one-on-one interviews are popular types of VOC collection techniques.
Without surveying the customers adequately, it is difficult to know which features of
a product or a service will contribute to its success or failure or to understand why.
Surveys are useful in some situations, but there are weak in terms of getting the types
of data necessary for new design.
Kano analysis 13 is a tool that can be used to classify and prioritize customer
needs. This is useful because customer needs are not all of the same kind, not all have
the same importance, and are different for different populations. The results can be
used to prioritize the team effort in satisfying different customers. The Kano model
divides the customer requirement into three categories (basic CTQs, satisfier CTQs,
and delighter CTQs).
Analytic hierarchy process (AHP) is a tool for multicriteria analysis that enables
the software DFSS team to rank explicitly an intangible factor against each other
in order to establish priorities. The first step is to decide on the relative importance
of the criteria, comparing each one against each other. Then, a simple calculation
determines the weight that will be assigned to each criterion: This weight will be
a value between 0 and 1, and the sum of weight for all criteria will be 8. This tool
for multicriteria analysis has another benefit for software DFSS project teams. By
breaking down the steps in the selection process, AHP reveals the extent to which
team members understand and can evaluate factors and criteria. The team leaders can
use it to simulate discussion of alternatives.
Pareto chart 14 provides facts needed for setting priorities. Typically, it organizes
and displays information to show the relative importance of various problems or
causes of problems. In DFSS, it can be used to prioritize CTQs in the QFD from
importance perspectives. It is a form of a vertical bar chart that puts items in order
(from the highest to the lowest) relative to some measurable CTQ importance. The
chart is based on the Pareto principle, which states that when several factors (or
requirements) affect a situation, a few factors will account for most of the impact.
The Pareto principle describes a phenomenon in which 80% of variation observed in
everyday processes can be explained by a mere 20% of the causes of that variation.
Placing the items in descending order of frequency makes it easy to discern those
13 See Chapter 12.
14 See Chapter 1.