Analyze each of the following investigations, or arguments, and indicate which of the methods of causal reasoning—Mill’s methods—are being used in each of them:

Undoubtedly the outstanding point of departure of industrial social psychology was the series of studies performed in the Hawthorne plant of the Western Electric Company, starting in 1927. These were conducted by three Harvard professors, Elton Mayo, F. J. Roethlisberger, and T. N. Whitehead, and by W. J. Dickson of Western Electric. The original aim of the studies was to obtain concrete data on the effects of illumination, temperature, rest periods, hours of work, wage rate, etc., upon production. A group of six girls, average workers, were chosen for the experiment; their task was the assembly of telephone relays. Almost from the beginning, unexpected results appeared: The production rate kept going up whether rest periods and hours were increased or decreased! In each experimental period, whatever its conditions, output was higher than in the preceding one. The answer seemed to lie in a number of subtle social factors. . . . As Homans summarizes it, the increase in the girls’ output rate “could not be related to any change in their conditions of work, whether experimentally induced or not. It could, however, be related to what can only be spoken of as the development of an organized social group in a peculiar and effective relation with its supervisors.”
—S. Stansfeld Sargent and Robert C. Williamson, Social Psychology, 1966