We study the evolution of social distance among economists over the period 1970–2000. While the number of economists has more than doubled, the distance between them, which was already small, has declined significantly. The key to understanding the short average distances is the observation that economics is spanned by a collection of interlinked stars. A star is an economist who writes with many other economists, most of whom have few coauthors and generally do not write with each other.

Abstract We study how knowledge about the social network of an individual researcher, as embodied in his coauthor relations, helps us in developing a more accurate prediction of his or her future productivity. We find that incorporating information about coauthor networks leads to a modest improvement in the accuracy of forecasts on individual output, over and above what we can predict based on the knowledge of past individual output. Second, we find that the informativeness of networks dissipates over the lifetime of a researcher's career. This suggests that the signaling content of the network is quantitatively more important than the flow of ideas.