The Seven Basic (B7) Tools


This chapter introduces a set of quality tools that are particularly useful in process improvement and problem-solving aspects of the software development process. A few of these tools are also useful in many design-related activities. These tools are popularly known as the Seven Basic (B7) Tools of Quality: flowcharts, Pareto diagrams, cause-and-effect diagrams, scatter diagrams, check sheets, histograms, and control charts (see Table 6.1).[1], [2], [3] These tools were originally developed by Kaoru Ishikawa, one of the pioneers of the Japanese quality movement (see Sidebar 6.1). Ishikawa's original list did not include flowcharts; instead, it had graphs as one of the tools. B7 has been part of SPC, a quality management system that uses a set of tools to analyze, control, manage, and improve process quality. But not all seven tools are quantitative, let alone statistical. The flowchart is simply a visual description of a process. A cause-and-effect diagram is a brainstorming-based problem-solving procedure. Check sheets and Pareto diagrams are simply commonsense tools. Histograms, scatter diagrams, and control charts are the only statistical tools in the list.

Table 6.1. Process Improvement Tools and Their Applications

Quality Tool

What It Addresses

Major Application in a DFTS Process

Flowchart/process map

How can all the process steps and sequences be described visually?

Process improvement

Fine-tuning a process before automating it

Auditing

Communication tool

Pareto chart

Which problems matter most?

Fault analysis

Peer review

Program maintenance

Root-cause analysis

Requirements development (QFD)

FMEA

Robust Design

Cause-and-effect diagram

What are the root causes of these problems?

Root cause analysis

Cause-and-effect graphing

Requirements development (QFD)

FMEA

Robust Design

Scatter diagram

What are the relationships between factors?

Requirements development (QFD)

Robust Design

Check sheet

How frequently does the problem occur, and how do you record it?

Everywhere

Histogram

What do the variations look like?

Process improvement

Requirements development (QFD)

Robust Design

Control chart

Which variations should be controlled, and in what manner

Process improvement

Requirements development (QFD)

Robust Design

Graph

What are the trends, over time, and fraction-wise distribution pattern of important variables?

Line charts in SPC/control charts

Pie and bar charts everywhere


B7 has been widely used in manufacturing in process-improvement initiatives such as Total Quality Management (TQM) and Six Sigma. They can also be used in upstream design phases, except for statistical tools such as control charts, histograms, and scatter diagrams, which require a larger volume of data to be statistically significant. The most frequently used B7 tools, such as cause-and-effect and Pareto diagrams, are not quantitative, let alone statistical. The tools were originally meant to make process analysis less complicated for the average factory worker in Japan, but now they constitute standard analytical tools to analyze quality problems and develop and identify solutions. Ishikawa believed that some 95% of quality-related problems can be solved with these tools. Their application has not yet been as extensive in software development. They are excellent in analyzing software measures and metrics, as discussed further in Chapter 15. They can and should be used in statistical control and process improvement of medium-size and large projects. Statistical tools are of comparatively limited value in upstream design and implementation activities, but other tools, such as cause-and-effect diagrams and Pareto analysis, are widely used throughout the DFTS process. For example, the cause-and-effect brainstorming procedure is widely used to generate data needed in QFD and FMEA (see Chapters 11 and 13, respectively). Table 6.1 lists a few typical applications of various B7 tools.

Sidebar 6.1: Kaoru Ishikawa: Developing a Specifically Japanese Quality Strategy[*]

The career of Kaoru Ishikawa in some ways parallels the economic history of contemporary Japan. Ishikawa, like Japan as a whole, learned the basics of statistical quality control from Americans. But just as Japan's economic accomplishments are not limited to imitating foreign products, so the country's quality achievementsand Ishikawa's in particulargo well beyond the efficient application of imported ideas.

Perhaps Ishikawa's most important contribution has been his key role in the development of a specifically Japanese quality strategy. The hallmark of the Japanese approach is broad involvement in qualitynot only top to bottom within the organization, but also from start to finish in the product life cycle.

The bottom-up approach is best exemplified by the quality circle. As a member of the editorial board of Quality Control for the Foreman, as chief executive director of Quality Control Circle Headquarters at the Union of Japanese Scientists and Engineers (JUSE), and as editor of JUSE's two books on quality circles (QC Circle Koryo and How to Operate QC Circle Activities), Ishikawa played a major role in the growth of quality circles.

One of Ishikawa's early achievements contributed to the success of quality circles. The cause-and-effect diagramoften called the Ishikawa diagram and perhaps the achievement for which he is best knownhas provided a powerful tool that can easily be used by nonspecialists to analyze and solve problems.

Although the quality circle was developed in Japan, it spread to more than 50 countries, a development Ishikawa never foresaw. Originally, Ishikawa believed circles depended on factors unique to Japanese society. But after seeing circles thrive in Taiwan and South Korea, he theorized that circles could succeed in any country that used the Chinese alphabet. Ishikawa's reasoning was that the Chinese alphabet, one of the most difficult writing systems in the world, can be mastered only after a great deal of study. Thus, hard work and a desire for education became part of the character of those nations. Within a few years, however, the success of circles around the world led him to a new conclusion: Circles work because they appeal to the democratic nature of humankind. "Wherever they are, human beings are human beings," Ishikawa wrote in a 1980 preface to the English translation of the Koryo.

In How to Operate QC Circle Activities, Ishikawa calls middle and upper management the parent-teacher association of quality control circles. Although circles were one of the earliest Japanese ideas about quality to be popularized in the West, Ishikawa was always aware of the importance of top management support. Support from the top is a key element in Japan's allencompassing quality strategy: company-wide quality control (CWQC), perhaps best described in Ishikawa's What Is Total Quality Control? The Japanese Way. Ishikawa's work with top management and CWQC covered decades. In the late 1950s and early 1960s, he developed quality control courses for executives and top managers. He also helped launch the Annual Quality Control Conference for Top Management in 1963.

As a member of the committee for the Deming Prize, Ishikawa developed the rigorous audit system that determines whether companies qualify for the prize. That audit requires the participation of the company's top executives. According to Ishikawa, that active, visible participationrather than the acclaim that goes with the prizeis the biggest benefit a winner receives.

If top-down, bottom-up involvement is one axis of CWQC, the other is an emphasis on quality throughout the product life cycle. Here, too, Ishikawa was involved starting in 1959, particularly in the development of a quality control system for new-product development.

Ishikawa was also involved in efforts to promote quality ideas throughout Japan, both in industry and among consumers. As chairman of the quality control National Conference committee for over 30 years, Ishikawa played a central role in the expanding scope of those conferences.

Ishikawa was also active in other efforts to promote quality. For example, he wrote several books explaining statistics to the nonspecialist. One of these, the Guide to Quality Control, was translated into English and became a staple in the quality training programs of corporations in the United States.

In addition, Ishikawa served as chairman of the editorial board of the monthly Statistical Quality Control and the quarterly Reports of Statistical Applications Research. As chairman of Japan's Quality Month committee, Ishikawa was involved in the selection of Japan's quality mark and quality flag.

Ishikawa was involved in Japanese and international standardization activities beginning in the 1950s. In his Shewhart Medal acceptance speech, Ishikawa called standardization and quality control "two wheels of the same cart." His emphasis might be surprising to some who think of standards as rigid and unchanging, but Ishikawa stressed the need for standards to change, and the dangers of clumsy enforcement of standards. In his view, effective standards must be built on a quality analysis of customer needs. When the analysis had not been conductedas is often the case with national and international standardsIshikawa recommended reliance on consumer needs rather than standards.

ASQ established the Ishikawa Medal in 1993 to recognize leadership in the human side of quality. The medal is awarded annually in honor of Ishikawa to an individual or team for outstanding leadership in improving the human aspects of quality.

Throughout his career, Ishikawa worked on very practical matters, but always within a larger philosophical framework. In its broadest sense, Ishikawa's work was intended to produce what he called a "thought revolution"new ideas about quality that could revitalize industry. The wide acceptance of many of Ishikawa's ideasand the numerous honors he has received from around the worldshow how successful his revolution has been.


[*] Reprinted with permission from www.asq.org. © 2006 American Society for Quality.




Design for Trustworthy Software. Tools, Techniques, and Methodology of Developing Robust Software
Design for Trustworthy Software: Tools, Techniques, and Methodology of Developing Robust Software
ISBN: 0131872508
EAN: 2147483647
Year: 2006
Pages: 394

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