The approach of using quantitative data to study and measure relationships within groups of people resulted in the development of sociometry.
[10] In 1943, Jennings completed her PhD thesis Leadership and Isolation: A Study of Personality in Interpersonal Relations,[11] eventually published by Longman, Greens, and Company.
Benjamin Karpman, a psychiatrist, describes the importance of Jennings's research in a review of the first edition of Leadership and Isolation for the Journal of Clinical Psychology.
In his review, Janowitz wrote that Leadership and Isolation "can be viewed as an ingenious empirical study which helped fashion sociometry as a research tool.
According to structural sociologist Linton C. Freeman, the empirical methods developed by Jennings and applied in Moreno's sociometry studies laid the groundwork for future social network research: "Clearly, with a great deal of help from Jennings and Lazarsfeld, Moreno had developed an approach that included all of the defining properties of social network analysis.
It was based on structural intuitions, it involved the collection of systematic empirical data, graphic imagery was an integral part of its tools and it embodied an explicit mathematical model.
The obvious conclusion is that, though the intuitive ideas came from Moreno, the completed research and the publications drew heavily on the contributions of Jennings.