Mathematical and statistical developments dominated the evolution of operations management from Taylor's time up to around the 1940. One exception was the Hawthorne studies conducted during the late 1920 and early 1930 by a research tears from Harvard Business School and supervised by the sociologist Elton Mayo. These experiments were designed to study the effects of certain environmental changes on the output of assembly workers at Western Electric's Hawthorne plant in Chicago Illinois. The unexpected findings reported in Management and the Worker by F. J. Brotherliness and W. J. Dickson? intrigued sociologists and students of traditional scientific management alike. To the surprise of the researchers changing the level of illumination for example had much less effect on the output than the way in which the changes were introduced to the workers. That is. reductions in illumination in some instances led to increased output because workers felt an obligation to their group to keep output high. Discoveries such as these had tremendous implications for work design and worker motivation and ultimately led to the establishment of personnel management and the human resources departments in most organizations.