With the persistent alarm being raised about terrorist violence by the media and government officials it is unsurprising that scholarship in this area has grown well beyond its traditional disciplinary boundaries (i.e., political science and international relations). As scholars from disciplines such as criminology [27, 30], computer science [11, 12, 35], economics [25], and others get more involved, more data sources have become available [1, 19, 28, 50] and more sophisticated analytical methods have been applied to terrorism research [14, 17, 30]. Yet, research on the effectiveness of counterterrorism measures has only incrementally improved in recent years [33].