Shewhart

Shewhart
Name	Walter A. Shewhart
Birth date	March 18, 1891
Birth place	Ironton, Ohio
Death date	March 11, 1967
Death place	Riverdale, Maryland
Nationality	American
Fields	Statistics, Industrial engineering, Quality control
Workplaces	Bell Labs, Western Electric
Alma mater	University of Illinois Urbana–Champaign, University of Michigan
Known for	Statistical process control, control chart, quality improvement

Shewhart Walter Andrew Shewhart was an American statistician and engineer widely regarded as the originator of modern statistical quality control and the control chart. He worked primarily at industrial research institutions where he developed methods combining experimental practice with statistical theory, influencing engineering, manufacturing, and management practices. His ideas shaped later developments by figures such as W. Edwards Deming, Joseph M. Juran, and institutions like American Society for Quality and International Organization for Standardization.

Biography

Shewhart was born in Ironton, Ohio and educated at the University of Illinois Urbana–Champaign and the University of Michigan. Early in his career he joined Western Electric and the research laboratories of Bell Labs, where he collaborated with industrial scientists and engineers on measurement, testing, and manufacturing problems. During his tenure at Bell Labs he interacted with contemporaries from AT&T, General Electric, and academic centers including Columbia University and Princeton University. Shewhart's professional contacts extended to figures in American Statistical Association and to international visitors from United Kingdom, Japan, and France, which aided dissemination of his work. He retired to Maryland but remained active in consulting with organizations such as National Bureau of Standards and professional societies until his death in Riverdale, Maryland.

Contributions to Statistics and Quality Control

Shewhart introduced a conceptual and practical framework that joined statistical reasoning with industrial practice, influencing fields represented by Institute of Industrial Engineers, American Society of Mechanical Engineers, and Society of Manufacturing Engineers. He emphasized the distinction between common causes and special causes of variation, a dichotomy later emphasized by W. Edwards Deming and cited in quality frameworks used by Toyota Motor Corporation and Ford Motor Company. Shewhart promoted the use of probability models and sampling in production settings, aligning with statistical traditions from Karl Pearson, Ronald A. Fisher, and Jerzy Neyman. His approach presaged methods in operations research and influenced standardization efforts by bodies such as International Electrotechnical Commission and American National Standards Institute.

Shewhart's methodological innovations informed developments in reliability engineering, metrology, and experimental design used in laboratories at Massachusetts Institute of Technology, Stanford University, and Harvard University. His writings were read and applied by managers and engineers in companies like Western Electric, Bell Labs, General Motors, and consulting firms including McKinsey & Company.

Shewhart Control Chart

Shewhart devised the control chart as a graphical tool to separate assignable causes from random variation in production processes, a technique that became central to Statistical process control taught in courses at Columbia University and Iowa State University. The control chart uses statistical limits—often derived from empirical standard deviation estimates—paralleling inference techniques from Ronald A. Fisher and sampling concepts associated with Jerzy Neyman and Egon Pearson. Industrial adoption of control charts occurred in contexts such as telephony at Bell System, wartime production programs coordinated by U.S. War Production Board, and postwar manufacturing expansions at General Motors and Boeing.

Variants and extensions of the Shewhart chart—like cumulative sum charts popularized by E. S. Page and exponentially weighted moving average charts developed by S. W. Roberts and Geoffrey E. P. Box—built on his foundational idea. Training programs by organizations such as American Society for Quality and curricula at Georgia Institute of Technology and Purdue University incorporate Shewhart charts in quality assurance and industrial statistics courses.

Influence on Statistical Process Control and Industry

Shewhart's ideas directly influenced practitioners and theorists including W. Edwards Deming, Joseph M. Juran, Philip B. Crosby, and Kaoru Ishikawa. Deming adapted Shewhart's cycle of specification, production, and improvement into management teachings that shaped industrial policy in Japan and guided revitalization of companies like Toyota Motor Corporation and Nissan Motor Company. Shewhart's distinction between assignable and common causes informed regulatory and quality frameworks at Food and Drug Administration, Occupational Safety and Health Administration, and manufacturing standards promulgated by International Organization for Standardization.

In academia Shewhart's concepts seeded research in statistical decision theory at University of California, Berkeley and quality engineering programs at Northwestern University and University of Michigan. His influence extended to defense and aerospace programs at Lockheed Martin and Northrop Grumman, where SPC methods were incorporated into reliability and systems engineering. Internationally, national statistical agencies and standards bodies, including National Institute of Standards and Technology equivalents in United Kingdom and Japan, promoted Shewhart-based methodologies.

Selected Works and Publications

- "Economic Control of Quality of Manufactured Product" (1931) — seminal monograph influencing Bell Labs practice and industrial statistics curricula at Iowa State University and Cornell University. - Numerous Bell System technical memoranda and internal reports distributed to engineers at Western Electric, AT&T, and technical societies such as Institute of Radio Engineers. - Papers and lectures presented to American Statistical Association and Institute of Mathematical Statistics, later cited by scholars from Columbia University, Stanford University, and Massachusetts Institute of Technology.

Category:American statisticians Category:Quality control Category:Industrial engineers