After 9/11

Using time-series procedures, the authors investigate whether transnational terrorism changed following 9/11 and the subsequent U.S.-led “war on terror.” Perhaps surprising, little has changed in the time series of overall incidents and most of its component series. When 9/11 is prejudged as a break date, the authors find that logistically complex hostage-taking events have fallen as a proportion of all events, while logistically simple, but deadly, bombings have increased as a proportion of deadly incidents. These results hold when they apply the Bai-Perron procedure in which structural breaks are data identified. This procedure locates earlier breaks in the mid-1970s and 1990s. Reasonable out-of-sample forecasts are possible if structural breaks are incorporated fairly rapidly into the model.

[1]  Richard Clutterbuck.  Terrorism in an Unstable World , 1994 .

[2]  Todd Sandler,et al.  Counterterrorism , 2005 .

[3]  Paul Wilkinson,et al.  Terrorism Versus Democracy: The Liberal State Response , 2000 .

[4]  Edward Moxon-Browne.  Europe's red terrorists: the fighting communist organizations , 1993 .

[5]  T. Sandler,et al.  Is Transnational Terrorism Becoming More Threatening? , 2000 .

[6]  Michael K. Reiter,et al.  Homeland Security , 2004, IEEE Internet Comput..

[7]  Chris Quillen,et al.  A Historical Analysis of Mass Casualty Bombers , 2002 .

[8]  Iain McLean,et al.  State of the Union , 2005 .

[9]  T. Sandler,et al.  A Theoretical Analysis of Transnational Terrorism , 1983, American Political Science Review.

[10]  Bruce Hoffman,et al.  Rethinking Terrorism and Counterterrorism Since 9/11 , 2002 .

[11]  P. Perron,et al.  Estimating and testing linear models with multiple structural changes , 1995 .

[12]  Walter Enders,et al.  Figure 2 : DEATH Incidents and Forecast Errors DEATH Incidents , 2004 .

[13]  J. Galloway,et al.  The state of the union. , 1970, Lancet.

[14]  P. Perron,et al.  Computation and Analysis of Multiple Structural-Change Models , 1998 .

[15]  T. Sandler,et al.  An economic perspective on transnational terrorism , 2004 .

[16]  W. Landes,et al.  An Economic Study of U.S. Aircraft Hijacking, 1960-1976 , 1977 .

[17]  William M. Landes,et al.  An Economic Study of U. S. Aircraft Hijacking, 1961-1976 , 1978, The Journal of Law and Economics.

[18]  Walter Enders,et al.  The Effectiveness of Antiterrorism Policies: A Vector-Autoregression-Intervention Analysis , 1993, American Political Science Review.

[19]  Bruce Hoffman,et al.  The confluence of international and domestic trends in terrorism , 1997 .

[20]  P. Perron,et al.  The Great Crash, The Oil Price Shock And The Unit Root Hypothesis , 1989 .

[21]  Chris Quillen.  Mass Casualty Bombings Chronology , 2002 .

[22]  T. Sandler,et al.  Collective Action and Transnational Terrorism , 2003 .