Software Quality Function Deployment (SQFD)

Quality Function Deployment (QFD) originated in Japan in 1966 when Yoji Akao introduced it there. It crossed to North America in the early 1980s. QFD is a visual planning tool that supports concurrent engineering. It provides a systematic, measured approach to determining what is of value to customers and how customers perceive and rate important aspects of competing products. It determines how different engineered features contribute to overall customer satisfaction. It is a concurrent engineering method that can be used to simultaneously solve multi-dimensioned problems in an objective way with group input and consensus.

Kobe shipyards in Japan, Toyota Autobody, Ford, Proctor and Gamble, Chrysler, General Electric (Aircraft Engines) are some of the big names that have used QFD to good effect. In 1984 companies began using QFD methods in software development thus introducing Software Quality Function Deployment (SQFD) to the world. When SQFD is used to focus on customer needs early in the Software Development Life Cycle, it results in fewer changes to an application during the design, coding and maintenance phases. The quality of the product is enhanced over other methods of specification, as SQFD ensures, by customer focus and technical feature optimisation, that the right product is specified. SQFD creates a closed loop when implemented properly that lowers costs, and improves timeliness, productivity and quality. These factors often in turn, lead to increased market share and profitability.

Toyota Autobody

• 430, 000 units produced at $71 per unit in 1974. This equalled an annual cost of $30,530,000 or 1.5 times their annual profit.
• QFD was introduced into process planning and production planning to utilise ideas and participation of plant workers.
• QFD activities from January 1977 through April 1984 resulted in:
  • A 61% reduction in product launch costs.
  • Time to market was reduced by 33%.
  • Measured quality was improved by 30%.

(Kliewer, Liu, Stephen, Weening, University of Calgary, Canada, web site 1998)

The success of a software organisation stems from customer satisfaction. This satisfaction comes from concentrating on building a quality product, and this is where SQFD has been found to add value.

The Japanese Experience

Japanese companies using QFD have:

• Reduced design cycle time by 30 to 50%.
• Reduced engineering changes by 30 to 50%.
• Reduced start-up costs by 20 to 60%.

(Shores A.R., A TQM Approach to Achieving Manufacturing Excellence, ASQC Quality Press, 1990)

Software quality has two important aspects:

• Maximising the value of software (SQFD). Value is designed in at requirements stage, where so many errors normally occur. The software engineer needs to concentrate the teams' best efforts on those technical design requirements that will maximise overall customer value and priorities.
• Minimisation of defects in software (software inspections, validation testing). This traditional view is more common, however technically good software that does not meet customer expectations, may be of low value.

SQFD helps to overcome three major problems in development of products, namely:

• Disregard for customer requirements (the voice of the customer).
• Loss of information (inherent in sequential processes, because of a broken telephone effect).
• Different individuals and functions working to different requirements.

SQFD makes an important transition from reactive to preventative quality control. SQFD avoids many problems caused by differences in language, perceptions, knowledge, experiences and values of parties, by using teams representing all relevant stakeholders in a given project. This allows projects using SQFD to respond quickly and accurately to changing customer requirements, technology and competitor moves.
The SQFD method is both systematic and quantifiable. It is a front-end requirements elicitation technique, which can precede any software development life cycle. SQFD documentation is concise and binds all decisions back to customer requirements and priorities in the face of competing products and available technical solutions in a traceable way. A knowledge base is built up and ideas can often be re-used in other projects. The process does cost more in the requirements elicitation, prioritisation and specification stages, but products benefit from designing quality in. These benefits include fewer requirements changes, less rework, and a direct and measured documented link to customers needs, competing products, and technical solution elements.

SQFD has been used successfully by many IT organisations such as AT&T, Hewlett Packard, IBM, Texas Instruments and Digital.

SQFD improves communication between departments since teams are cross functional, involving customers, sales people, managers, developers, system architects, engineers, business analysts, testers and other stake holders. The communications are systematised and well documented in a succinct way for traceability and process integrity through the design and development process. This also gives benefits when new or changed customer or design requirements are involved. The process offers some reuse possibilities.