Quality Controls

BIBLIOGRAPHY

Quality control is a management process that provides information about the conformity of either products or services to prespecified standards of utility. This function first became professionalized during the nineteenth century as a means for addressing the growing problem of the asymmetric distribution of product information that attended the rise of giant business enterprise and the emergence of mass markets. On the firm level, the growing scale and scope of manufacturing created pressure for the development of new metrics for informing management decision processes. While cost accounting was effective in ascertaining profitability, it provided little insight into the factors that affected output quality. This represented a potentially serious informational shortcoming as the largest manufacturing entities sought the realization of economies of scale through long production runs of standardized products.

On the consumer level, industrialization changed the nature of the relationship between consumers and producers. Unlike the shop economy of the preindustrial era, the line of communication connecting these groups for resolving quality issues became attenuated by the intermediation of longer supply chains and more impersonalized distributional arrangements. Industrialization also displaced indirect modes for assuring quality through guild or craft union validation of artisan skills through apprentice, journeyman, or master status. Many firms following scientific management principles enhanced the efficiency of their production lines by systematizing work effort through worker time-and-motion studies. These initiatives de-emphasized the role of the skilled craft practitioner and encouraged the placement of greater reliance in mass production on cheaper un- or semiskilled labor.

Quality assessment had within its compass the ability to surmount the problems of informational asymmetries about product quality in two ways. First, firms could apply quality standards to define what constituted a steady-state condition in their manufacturing. This new firm-specific knowledge, used in conjunction with accounting and financial data, could enhance efficiency by extending organizational capacities for planning, coordinating, controlling, monitoring, and evaluating production activities. Such study was also important to corporations in determining the economic limits of product inspection. Second, the dissemination of reliable information about product standards helped to eliminate asymmetries in external markets, thus contributing to a reduction in consumer risk perceptions. Such knowledge also helped consumers weigh more objectively the tradeoff between performance benefits and costs in project analysis. Moreover, quality standards affected producer reputations by providing consumers with a basis for making grading comparisons between the output of rival suppliers.

Initially the focus of quality assessment centered on products rather than processes. The measurement of key design attributes and their alignment with engineering design standards became paramount. This involved the use of such measurement devices as gauges, calipers, jigs, and meters to determine if products met physical and performance requirements detailed in specification documents and blueprints. Such evaluation also involved destructive testing to measure the physical limits of materials. These early approaches, however, proved insufficient because they lacked an effective means for assessing the significance of test data. The statistical summarizations of this period were mere enumerations, devoid of a scientific basis for defining the nature of quality or for determining whether it had been effectively controlled in production.

The Bell System in the United States achieved a major breakthrough in surmounting problems of quality definition and analysis in the 1920s by developing new approaches that emphasized process and probability theory. The initial focus of innovation centered on the captive manufacturing subsidiary Western Electric, which supplied most of the material requirements of the Regional Bell Operating Companies. Such methodological innovation responded to regulatory pressures to provide more economical and efficient communication services through the deployment of more reliable equipment. In 1925, quality-control research centered on the inspection engineering department of the Bell Laboratories. Prime movers in establishing what became known as “statistical quality control” included Walter A. Shewhart of the theory and special studies unit and Harold F. Dodge of the inspection methods and results unit. Working in close coordination with the firm’s manufacturing departments, they defined a unifying theory and set of applied methodologies that revolutionized quality engineering by 1928.

The assessment of quality at Bell benefited from several new analytical constructs based in probability theory. The control chart, for example, exploited the properties of the normal curve to clarify the economic limits of control. It distinguished between “common causes of errors” that were random and uncontrollable and “assignable causes of error” that could be rectified through management action. The trade-offs inherent in sample selection and evaluation became better illuminated from the specification of consumer’s risk (Type I) involving the incorrect acceptance of an unreliable sample and producer’s risk (Type II) involving the incorrect rejection of a valid sample. Customer planning was facilitated by the determination of the “average outgoing quality limit,” a steady-state metric indicating the maximum number of defects in product shipments. In these and other ways probability theory increased the analytical power, flexibility, and range of quality engineering.

The new knowledge subsequently gained higher professional status in the United States and abroad. Shewhart taught the first collegiate course in quality engineering at Stevens Institute of Technology during the late 1930s, and soon thereafter Armand V. Feigenbaum of General Electric wrote the first doctoral dissertation on the subject at the Massachusetts Institute of Technology. During World War II, the new techniques were applied extensively in the U.S. Army Ordnance Corps with the assistance of Bell System advisers. W. Edwards Deming was also instrumental in organizing training programs for national defense industries through the War Production Board. In the postwar era, engineers with the Civil Communication Service of Supreme Command Allied Powers helped to revive interest in the topic in Japan. The Japanese Union of Scientists and Engineers began sponsoring courses presented by Deming, Joseph Juran, and others. In 1947 a new professional association, the American Society for Quality Control (now the American Quality Society), was founded. In 1956 the European Organization for Quality Control was formed.

While manufacturing quality control has continued to evolve, the new frontier involves the use of its concepts to address problems of informational asymmetry for services. The U.S. General Accounting Office, for example, reflected a concern about quality in audits of federally financed projects by requiring the evaluation of program effectiveness and results. Studies of environmental pollution, for example, often employ the probabilistic tools initially developed for industry. The notion of quality has also affected professional governance, albeit in a less quantitative way. The American Institute of Certified Public Accountants since the 1980s has required accounting firms to evince compliance with practice-quality standards as a condition of membership.

BIBLIOGRAPHY

Bayart, Denis. 2000. How to Make Chance Manageable: Statistical Thinking and Cognitive Devices in Manufacturing Control. In Cultures of Control, ed. Miriam R. Levin, 153–176. Amsterdam, Harwood Academic Publishers.

Deming, W. Edwards. 1986. Out of the Crisis. Cambridge, MA: MIT Press.

Feigenbaum, Armand V. 1983. Total Quality Control, 3rd ed. New York: McGraw-Hill.

Juran, Joseph M. 2004. Architect of Quality: The Autobiography of Dr. Joseph M. Juran. New York: McGraw-Hill.

Miranti, Paul J., Jr. 2005. Corporate Learning and Quality Control at the Bell System, 1877–1929. Business History Review 79 (spring): 39–72.

Shewhart, Walter A. 1931, Economic Control of Quality of Manufactured Product. New York: Van Nostrand.

Paul J. Miranti