Estimating the historical and future probabilities of large terrorist events

Quantities with right-skewed distributions are ubiquitous in complex social systems, including political conflict, economics and social networks, and these systems sometimes produce extremely large events. For instance, the 9/11 terrorist events produced nearly 3000 fatalities, nearly six times more than the next largest event. But, was this enormous loss of life statistically unlikely given modern terrorism's historical record? Accurately estimating the probability of such an event is complicated by the large fluctuations in the empirical distribution's upper tail. We present a generic statistical algorithm for making such estimates, which combines semi-parametric models of tail behavior and a nonparametric bootstrap. Applied to a global database of terrorist events, we estimate the worldwide historical probability of observing at least one 9/11-sized or larger event since 1968 to be 11-35%. These results are robust to conditioning on global variations in economic development, domestic versus international events, the type of weapon used and a truncated history that stops at 1998. We then use this procedure to make a data-driven statistical forecast of at least one similar event over the next decade.Comment: Published in at http://dx.doi.org/10.1214/12-AOAS614 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Border Security: Understanding Threats at U.S. Borders

[Excerpt] The United States confronts a wide array of threats at U.S. borders, ranging from terrorists who may have weapons of mass destruction, to transnational criminals smuggling drugs or counterfeit goods, to unauthorized migrants intending to live and work in the United States. Given this diversity of threats, how may Congress and the Department of Homeland Security (DHS) set border security priorities and allocate scarce enforcement resources? In general, DHS’s answer to this question is organized around risk management, a process that involves risk assessment and the allocation of resources based on a cost-benefit analysis. This report focuses on the first part of this process by identifying border threats and describing a framework for understanding risks at U.S. borders. DHS employs models to classify threats as relatively high- or low-risk for certain planning and budgeting exercises and to implement certain border security programs. Members of Congress may wish to use similar models to evaluate the costs and benefits of potential border security policies and to allocate border enforcement resources. This report discusses some of the issues involved in modeling border-related threats

Trafficking in Persons: U.S. Policy and Issues for Congress

[Excerpt] This report focuses on international and domestic human trafficking and U.S. policy responses, with particular emphasis on the TVPA and its subsequent reauthorizations. The report begins with a description of key TIP-related definitions and an overview of the human trafficking problem. It follows with an overview of major foreign policy responses to international human trafficking. The report then focuses on responses to trafficking into and within the United States, examining relief for trafficking victims in the United States and discussing U.S. law enforcement efforts to combat domestic trafficking. The report concludes with an overview of current anti-trafficking legislation and an analysis of policy issues

FDI, terrorism and the availability heuristic for U.S. investors before and after 9/11

We record the existence of an availability heuristic that is reflected in disaster myopia of U.S. investors and exists prior to the attacks of 9/11. We argue that this is fueled by an aggregate experience hypothesis effect, resulting in a pronounced increase in the sensitivity of U.S. stock prices to terrorist attacks on foreign soil. After 9/11, stock prices react proportionally to the size of an attack and the share of FDI stock held in the region by the sector in which firms operate. This effect, non-existent prior to 2002, has become increasingly strong in recent years

Assessing, Managing, and Financing Extreme Events: Dealing with Terrorism

This paper discusses new challenges we face with terrorism as a catastrophic risk by focusing on risk assessment, risk management as well as risk financing issues. The special characteristics of terrorism compared with major natural hazards call for the development of public-private partnerships, as recognized in November 2002 when the Terrorism Risk Insurance Act of 2002 (TRIA) was passed. This paper shows, however, that the temporary insurance system established by TRIA is neither a complete answer nor a definitive one. It raises fundamental questions for U.S. insurers as to how they will estimate the risk in order to set premiums for terrorist coverage that they now must offer to their clients. We discuss some of the most recent developments of terrorism models for helping insurers and reinsurers assess the premiums they should charge and how much coverage they can assume as well as for firms to better understand their exposure. Since the passage of TRIA, the current level of demand for insurance coverage has remained low and we discuss some factors that may contribute to it. After presenting alternative foreign public-private partnerships and discussing the potential role for terrorist catastrophe bonds, we provide some features of a more sustainable program for terrorism insurance in the U.S. after December 31, 2005.