Ever since Edwards Deming (1986) and Joseph Juran (1989) expanded the debate about quality from their pioneering work with Japanese manufacturing companies in the 1950s to the broader application of total quality control and management in all industry and service sectors, the debate has always recognized the interaction between the product development process and the intrinsic quality of the product. However, over the past 10 years , there has emerged a philosophical gap between the advocates of process improvement and those concentrating on product improvement.
Following Deming's assertion that 80% of all quality problems can be attributed to failures in the system (process) rather than individual worker-induced defects, much of the total quality management (TQM) thrust has concentrated on process improvement.
In the industry, quality standards such as the ISO 9000 series and more, in software, models such as the capability maturity model (CMM) are similarly oriented toward improvement and standardization of the software development process. 
Although these process improvement initiatives are clearly valid, they beg a critical question: Does product development process improvement result automatically in improvement of product quality?
Although this assumption is, in the main, true, it accepts that the required quality of the product is both understood by the development group and that the required quality is designed into the product development process. As a simple example of this problem, Superb Sausages Pty Ltd., a sausage manufacturer, determines that its customers require a gourmet chicken and strawberry sausage. Using their standard sausage design methodology, the sausage designers determine the ingredients , volumes , and so on required by the new sausage. They produce a sample batch and after a successful taste test begin mass production. However, after mashing up 1,000 kilos of chicken and strawberries, the mashing machine clogs up, as it was not designed to process a soft fruit. The sausage (product) has the required quality specification but the sausage mashing machine (development process) failed to implement the required quality.
In the area of business project development, the same problem regarding process and product quality exits. Does the installation of a standard development methodology, quality assurance procedures, and rigorous project management processes guarantee the development and shipping of quality systems?
It is revealing to note that in the vast majority of quality-oriented books, articles, and "packaged" total quality control (TQC) methodologies, the need to tightly couple the product development process and the product quality is completely ignored.
Linking Product and Process Quality: QFD
In Japan, the coupling of process development to product quality is achieved through a technique that has little exposure in the populist quality push in the United States and Australia. QFD was developed by Yoki Akao (1990) and others in the late 1980s specifically to address the linking between product development process and intrinsic product quality. Recently, articles by John Hauser and Don Claussing in the Harvard Business Review (1988), by Rich Zultner in American Programmer (1992), and books by Bob King (1989) and Lou Cohen (1995) have begun to draw attention to the use of this powerful technique in manufacturing and software development.
In essence, QFD is a rigorous and highly structured process involving the precise definition of required product quality and the deployment of tailored processes designed to embed the quality requirements throughout the product development process. QFD provides the missing link between process and product quality and it is a major factor behind the impressive growth in Japan's quality reputation.
The traditional approach to attempting to link product and process improvement is the use of formal quality plans. The standard procedure included in most project management approaches is to require the project manager to detail the process that he or she is going to use to assure quality. This would include what project or system development tools, technologies, and support are to be used in the project and what external quality assurance reviews are to be conducted . In many cases, these quality plans are nothing more than a simple checklist of the development processes that should be followed, similar to those loved by traditional auditors . Such checklists are important but they ignore a fundamental question: What is the required quality for the product or system? For example, when conducting a quality review of a system design, what does the review team look for? Do they check whether the design is efficient, follows the organizational standards, is compliant with the company's policy or IT architecture, or has inherent defects?
As in QFD, any process for assuring system quality must start with an unambiguous statement of the required system quality.