A Time-Series Analysis of Terrorism: Intervention, Displacement, and Diffusion of Benefits

This paper discusses the perception that displacement in terrorism is inevitable; that antiterrorism efforts merely relocate terrorism in some way. Using quarterly time-series data from the Global Terrorism Database (1994–2013) and the vector autoregression framework, we test the following hypothesis: the target-hardening efforts within the United States (US) after September, 11, 2001 reduce attacks on domestic US targets, but increase attacks on US targets abroad. To provide a more comprehensive test, we also provide dynamic impact factors and variance decompositions. The results of this intervention analysis show no support for displacement, and instead provide support for a diffusion-of benefits hypothesis. We also discuss how criminological and especially crime-prevention knowledge can guide and encompass the study of terrorism.