Abstract
In this talk, I will survey empirical approaches to causal inference in networks and describe a series of large-scale randomized experiments and causal observational studies of peer influence to explore the behavioral dynamics catalyzed by peer effects or social spillovers in human behavior and opinion formation. I will discuss implications of peer effects for bias in online ratings, social advertising, human health interdependence and the ability to generate cascades of behavior through peer to peer influence in networks.