In this, Whitehead's "golden rule" was to "never measure more than is absolutely necessary". The Hawthorne experiments studied worker productivity at a Western Electric factory. They were originally intended to study the effects of lighting on productivity, but instead determined that workers reacted positively to the changing conditions of the experiment, and that their productivity decreased again when the experiment ended. Whitehead, following the lead of Jean Piaget, took the approach of carefully documenting the behavior of a small sample of workers over a long period of time. His analysis of the Hawthorne experiments used rigorous statistics to argue "that personal and social relationships had been the dominant factors" in these effects. His work has been criticized as "complex and poorly presented", with unoriginal ideas "expressed in infuriatingly vague prose". Nevertheless, his work is important as the only original mathematical analysis of the experimental data and the only complete record of the entire run of the experiments. Besides his work on the Hawthorne experiments, Whitehead is known for pioneering the development of the fields of human relations, organizational behavior, and human resource management, and for his 1936 book "Leadership in a Free Society" on the structure and organization of human activity.