A principal reason that losses from catastrophic risks have been increasing over time is that more individuals and firms are locating in harm's way while not taking appropriate protective measures. Several behavioural biases lead decision-makers not to invest in adaptation measures until after...

There are many social situations in which the actions of different agents reinforce each other. These include network effects and the threshold models used by sociologists (Granovetter, Watts) as well as Leibenstein's "bandwagon effects." We model such situations as a game with increasing...

Shareholder valuations are economically and statistically positively correlated with more powerful independent directors, their power gauged by social network power centrality measures. Sudden deaths of powerful independent directors significantly reduce shareholder value, consistent with...

Can we identify the members of a community who are best- placed to diffuse information simply by asking a random sample of individuals? We show that boundedly-rational individuals can, simply by tracking sources of gossip, identify those who are most central in a network according to "diffusion...

We examine how participation in a microfinance program diffuses through social networks. We collected detailed demographic and social network data in 43 villages in South India before microfinance was introduced in those villages and then tracked eventual participation. We exploit exogenous...

The Schelling model of a "tipping point" in racial segregation, in which whites flee a neighborhood once a threshold of nonwhites is reached, is a canonical model of strategic interdependence. The idea of "tipping" explaining segregation is widely accepted in the academic literature and popular...

We define a general class of network formation models, Statistical Exponential Random Graph Models (SERGMs), that nest standard exponential random graph models (ERGMs) as a special case. We provide the first general results on when these models' (including ERGMs) parameters estimated from the...

We model tipping as a game-theoretic phenomenon and investigate the connection between supermodular games, tipping of equilibria and cascading, and apply the results to issues that arise in the context of homeland security and computer security. We show that tipping and cascading can occur in...

In an interdependent world the risks faced by any one agent depend not only on its choices but also on those of all others. Expectations about others' choices will influence investments in risk-management, and the outcome can be sub-optimal investment all round. We model this as the Nash...

This paper extends our earlier analysis of interdependent security issues to a general class of problems involving discrete interdependent risks with heterogeneous agents. There is a threat of an event that can only happen once, and the risk depends on actions taken by others. Any agent's...