The question asks to identify the management thinker who developed the theory of “Variation”. Understanding variation is crucial in quality management, a field where several prominent thinkers have made significant contributions.

Let's examine the concept of variation in the context of management and quality.

Understanding the Theory of Variation in Management

In management, especially in quality management and process improvement, variation refers to the differences or inconsistencies that occur in processes or outputs. No two products or services are exactly alike; there is always some degree of variation. This variation can be due to various factors related to materials, equipment, people, methods, or the environment.

The theory of variation emphasizes that understanding and reducing unwanted variation is key to improving quality, predictability, and efficiency in any system. Variation makes outcomes unpredictable, increases costs, and can lead to defects or customer dissatisfaction.

There are typically two types of variation:

• Common Cause Variation: This is inherent in the process and is due to the system itself. It's random and affects everyone working in the system. Reducing common cause variation usually requires changing the process itself.
• Special Cause Variation: This is due to unusual or specific circumstances not typically part of the process. It's assignable to a specific event or factor and can often be identified and eliminated without changing the entire system.

Managing variation involves using statistical tools and methods to measure, analyze, and control these variations. The goal is often to reduce common cause variation and eliminate special cause variation.

Identifying the Management Thinker

Among the listed thinkers, one is particularly renowned for his work on quality management and the fundamental importance of understanding and managing variation. Let's consider the options:

• Peter Drucker: Known as the father of modern management, Drucker's contributions include Management by Objectives (MBO), decentralization, and the concept of knowledge work. While his work is foundational to management, he is not primarily associated with the theory of variation.
• Mouton and Blake: Robert R. Blake and Jane S. Mouton developed the Managerial Grid (later Leadership Grid), a model describing different leadership styles based on concern for people and concern for production. Their work focuses on leadership and organizational behaviour, not specifically the theory of variation.
• Edward Deming: W. Edwards Deming was a statistician, engineer, and management consultant. He is widely regarded as one of the most influential thinkers in total quality management (TQM). A cornerstone of his philosophy is the profound understanding of variation. His work, including his 14 Points for Management and his emphasis on statistical process control (SPC), is deeply rooted in the theory of variation and its impact on quality and productivity. Deming taught that management's primary role is to understand and manage the systems, and that reducing variation within these systems is critical for improvement.
• Henry Fayol: A classical management theorist, Henry Fayol is best known for his 14 Principles of Management and his functions of management (planning, organizing, commanding, coordinating, controlling). His work is foundational to administrative theory but does not specifically address the theory of variation in the way Deming's work does.

Based on their major contributions, W. Edwards Deming is the thinker who extensively developed and championed the theory of variation as a key principle for effective management and quality improvement.

Conclusion

The theory of variation, central to understanding and improving processes and quality, was significantly developed and promoted by Edward Deming. His insights into common and special causes of variation and the use of statistical methods to manage them are fundamental to modern quality practices.

Additional Information: Deming's Philosophy and Variation

Edward Deming's focus on variation was a central theme in his teaching. He argued that most problems in a system (up to 95% according to some interpretations of his work) are due to common cause variation inherent in the system itself, rather than special causes or individual worker performance. This perspective fundamentally shifted the focus of management from blaming individuals to improving the processes and systems they work within.

Deming advocated for the use of statistical thinking and tools, such as control charts, to distinguish between common and special causes of variation. Reacting to common cause variation as if it were a special cause (tampering) can actually increase variation and worsen the system's performance. Conversely, failing to identify and address special causes when they occur misses opportunities for significant improvement.

His 14 Points for Management provide a framework for organizational transformation, many of which indirectly or directly relate to understanding and managing variation, such as "Cease dependence on mass inspection; require instead proof that the process is right" and "Improve constantly and forever the system of production and service." These points emphasize building quality into the process by reducing variation, rather than trying to inspect defects out at the end.