Network insiders and observers: who can identify influential people?

Identifying influential people within a community to involve in a program is an important strategy of behavioral interventions. How to efficiently identify the most effective individuals is an outstanding question. This paper compares two common strategies: consulting ‘network insiders’ versus ‘network observers’ who have knowledge of but who do not directly participate in the community. Compared to aggregating information from all insiders, asking relatively fewer observers is more cost-effective, but may come at a cost of accuracy. We use data from a large-scale field experiment demonstrating that central students, identified through the aggregated nominations of students (insiders), reduced peer conflict in 56 middle schools. Teachers (observers) also identified students they saw as influential. We compare the causal effect of the two types of nominated students on peer outcomes and the differences between the two types of students. In contrast to the prosocial effects of central students on peer conflict, teacher nominees have no, or even antisocial, influence on their peers’ behaviors. Teachers (observers) generally nominated students with traits salient to them, suggesting that observer roles may systematically bias their perception. We discuss strategies for improving observers’ ability to identify influential individuals in a network as leverage for behavioral change.