GTD in Research

Borooah, Vani K. 2009. "Terrorist Incidents in India, 1998-2004: A Quantitative Analysis of Fatality Rates." Terrorism & Political Violence 21:476-498.

Using data from the University of Maryland's Global Terrorism Database II, this paper first provides information on the nature of terrorist incidents in India in the period 1998-2004: the Indian states that were worst affected by terrorist incidents and fatalities; the terrorist groups responsible for such incidents and their modus operandi. Next, the paper focuses on the issue of fatalities from terrorist incidents. It inquires into the extent to which the number of fatalities following an incident was influenced by the type of attack (bombings, armed assault, etc.) and the extent to which it was influenced by the type of terrorist group. By examining the number of fatalities resulting from terrorist attacks in India, the paper disentangles the influence on this number of attack type and attack group. Lastly, the paper applies Atkinson's concept of equality-adjusted income to terrorism to arrive at the concept of equality-adjusted deaths from terrorist incidents: in order to avoid spectacular incidents resulting in the loss of a large number of lives—as in New York on September 11, 2001 and in Mumbai 26-29 November 2008—“society” might be prepared to tolerate “low-grade” terrorism which resulted in a larger number of deaths in total but avoided a large number of deaths from a single iconic incident.

Chang, Charles and Ying Ying Zeng. 2011. “Impact of Terrorism on Hospitality Stocks and the Role of Investor Sentiment.” Cornell Hospitality Quarterly 52:165-175.

This study examines a comprehensive data set of all terrorist activities that directly affected Americans between 1973 and 2003, exploring the reaction of hospitality stocks to these events. Hospitality stocks’ returns following terrorist events are well in excess of those experienced by the rest of the stock market, beating the market by 10 to 15 percent per annum. These results persist despite controls for the type of event, number of casualties, location of the event, changes in market risk, and resulting impacts on room demand and average daily rates. The most severe one hundred events, after an initial negative reaction, are followed by returns nearly four times larger than those of the average event. Findings are consistent with sentiment playing a substantial role in hospitality stock returns.

Choi, Seung-Whan. 2010. “Fighting Terrorism through the Rule of Law?” Journal of Conflict Resolution 54:940-966.

The question of whether democratic institutions facilitate terrorist activities is a controversial one in current scientific studies of terrorism. Although the "rule of law" is an essential institutional pillar of any mature democracy, its direct effect on domestic and international terrorism remains unexplored. Conceiving democratic rule of law as the coexistence of effective and impartial judicial systems and citizens’ recognition of the law as legitimate, the author presents a causal explanation in which a high-quality rule of law is considered to dampen ordinary citizens’ opportunity and willingness to engage in political violence, protecting democracies from becoming victims of terrorism. Built on a cross-sectional, time-series data analysis of 131 countries during the period from 1984 to 2004, the author finds that, ceteris paribus, maintaining a sound rule of law notably reduces the likelihood of any type of terrorist events. In short, the rule of law instantiated in democratic institutions provides a formidable bulwark against terrorism.

Drakos, Konstantinos. 2010. “Terrorism Activity, Investor Sentiment, and Stock Returns.” Review of Financial Economics 19:128-135.

Motivated by the literature on investor sentiment and assuming that terrorist activity influences investor mood, in this paper we explore whether terrorism exerts a significant negative impact on daily stock market returns in a sample of 22 countries. The employed empirical specifications are based on flexible versions of the World CAPM, allowing for autoregressive conditional heteroscedasticity. The results suggest that terrorist activity leads to significantly lower returns on the day a terrorist attack occurs. In addition, the negative effect of terrorist activity is substantially amplified as the level of psychosocial effects increases. On the one hand, this evidence sheds light on the underlying mechanism via which terrorism affects stock markets while on the other hand, it provides further empirical support for the sentiment effect.

Dugan, Laura, and Gary LaFree, Alex R. Piquero. 2005. "Testing a Rational Choice Model of Airline Hijackings." Criminology 43:1031-1065.

Using data that combines information from the Federal Aviation Administration, the RAND Corporation and the GTD, we are able to examine trends in 1,101 attempted aerial hijackings that occurred around the world from 1931 to 2003. We have especially complete information for 828 hijackings that occurred before 1986. Using a rational choice theoretical framework, we use continuous-time survival analysis to estimate the impact of several major counterhijacking interventions on the hazard of differently motivated hijacking attempts and logistic regression analysis to model the predictors of successful hijackings. Some of these interventions use certainty-based strategies of target hardening to reduce the perceived likelihood of success. Others focus on raising the perceived costs of hijacking by increasing the severity of punishment. We also assess which strategies were most effective in deterring hijackers whose major purpose was related to terrorism. We found support for the conclusion that new hijacking attempts were less likely to be undertaken when the certainty of apprehension was increased through metal detectors and law enforcement at passenger checkpoints. We also found that fewer hijackers attempted to divert airliners to Cuba once that country made it a crime to hijack flights. Our results support the contagion view that hijacking rates significantly increase after a series of hijackings closely clustered in time—but only when these attempts were successful. Finally, we found that the policy interventions examined here significantly decreased the likelihood of nonterrorist but not that of terrorist hijackings. Journal Website

Enders, Walter, Todd Sandler, and Khrsrav Gaibulloev. 2011. "Domestic Versus Transnational Terrorism: Data, Decomposition, and Dynamics." Journal of Peace Research 48:319-337.

This article devises a method to separate the Global Terrorism Database (GTD) into transnational and domestic terrorist incidents. This decomposition is essential for the understanding of some terrorism phenomena when the two types of terrorism are hypothesized to have different impacts. For example, transnational terrorism may have a greater adverse effect than domestic terrorism on economic growth. Moreover, the causes of the two types of terrorism may differ. Once the data are separated, we apply a calibration method to address some issues with GTD data – namely, the missing data for 1993 and different coding procedures used before 1998. In particular, we calibrate the GTD transnational terrorist incidents to ITERATE transnational terrorist incidents to address GTD’s undercounting of incidents in much of the 1970s and its overcounting of incidents in much of the 1990s. Given our assumption that analogous errors characterize domestic terrorist events in GTD, we apply the same calibrations to adjust GTD domestic incidents. The second part of the article investigates the dynamic aspects of GTD domestic and transnational terrorist incidents, based on the calibrated data. Contemporaneous and lagged cross-correlations for the two types of terrorist incidents are computed for component time series involving casualties, deaths, assassinations, bombings, and armed attacks. We find a large cross-correlation between domestic and transnational terrorist incidents that persists over a number of periods. A key finding is that shocks to domestic terrorism result in persistent effects on transnational terrorism; however, the reverse is not true. This finding suggests that domestic terrorism can spill over to transnational terrorism, so that prime-target countries cannot ignore domestic terrorism abroad and may need to assist in curbing this homegrown terrorism.

Fahey, Susan, Gary LaFree, Laura Dugan, and Alex R. Piquero. Forthcoming. "A Situational Model for Distinguishing Terrorist and Non-Terrorist Aerial Hijackings, 1948-2007." Justice Quarterly.

Despite the centrality of situational variables to crime theories, they remain uncommon in criminology. Based on the hypotheses drawn from the literature on situational determinants of crime, we examine whether aerial hijackings perpetrated by terrorists are situationally distinct from other aerial hijackings. We define terrorist hijackings as those that include threatened or actual use of illegal force or violence to attain a political, economic, religious or social goal through fear, coercion, or intimidation. Other aerial hijackings include those perpetrated for transportation or extortion purposes. Using a newly updated dataset, we examined 1,019 aerial hijackings that occurred around the world from 1948 to 2007, out of which we classified 122 as terrorism. Results provide strong support for the argument that situational factors measuring organizational resources distinguish terrorist from non-terrorist aerial hijackings, and partial support for the argument that situational factors measuring publicity distinguish these events.

Gaibulloev, Khusrav, and Todd Sandler. 2011. "The Adverse Effect of Transnational and Domestic Terrorism on Growth in Africa." Journal of Peace Research 48:355-371.

This article investigates the adverse effects of domestic and transnational terrorism on income per capita growth for 51 African countries for 1970–2007, while accounting for cross-sectional (spatial) dependence and conflict (i.e. internal conflicts and external wars). The findings of the fixed-effects panel estimator suggest that transnational terrorism has a significant, but modest, marginal impact on income per capita growth. These results hold for two different terrorism event datasets. However, domestic terrorist events do not affect income per capita growth. Our findings differ from those in an earlier study on the impact of transnational terrorism on African growth, because we uncover a much more moderate effect. In our study, regional impacts and terrorism–conflict interactions effects are also distinguished. Moreover, our sample countries and period are more extensive. Our article contains a host of robustness checks involving macroeconomic and political variables that find virtually identical results. Alternative terrorist variables are also used, with little qualitative change in the findings. The absence of a domestic terrorism impact is surprising because there were many more domestic than transnational terrorist incidents in Africa. To promote growth, host and donor countries must direct scarce counter-terrorism resources to protect against transnational terrorism in particular. The modest impact of transnational terrorism on African growth means that developing countries' economies have been more resilient to terrorism than has been generally thought.

Godwin, Alex, Remco Change,Robert Kosara, and William Ribarsky. 2008. "Visual Analysis of Entity Relationships in Global Terrorism Database" Proceedings of SPIE 6983, 69830G; doi:10.1117/12.778084

With the increase of terrorist activity around the world, it has become more important than ever to analyze and understand these activities over time. Although the data on terrorist activities are detailed and relevant, the complexity of the data has rendered the understanding and analysis difficult. We present a visual analytical approach to effectively identify related entities such as terrorist groups, events, locations, etc. based on a 2D layout. Our methods are based on sequence comparison from bioinformatics, modified to incorporate the element of time. By allowing the user the freedom to link entities by their activities over time, we provide a new framework for comparison of event sequences. Our scoring mechanism is robust and flexible, giving the user the flexibility to define the extent to which time is considered in aligning entities. Incorporated with high interactivity, the user can efficiently navigate through tens of thousands of records recorded in over a hundred dimensions of data by choosing combinations of categories to examine. Exploration of the terrorist activities in our system reveals relationships between entities that are not easily detectable using traditional methods.

Greenbaum, Robert, Laura Dugan and Gary LaFree. 2007. "The Impact of Terrorism on Italian Employment and Business Activity." Urban Studies 44:1093-1108.

Despite the growth in research examining direct economic impacts of terrorism, the indirect impact of terrorism on the stability of local economies has generally been overlooked. Using panel data regression models and the GTD, we examine the impact of terrorism on employment and business outcomes in Italy from 1985 to 1997. We find that terrorist attacks reduce the number of firms and employment in the year following an attack. By disaggregating net outcomes into their component gross flows, we also find that these impacts are primarily attributable to reduced business formations and expansions. Journal Website

Huang, Julie, Laura Dugan, Gary LaFree, and Clark McCauley. 2008. "The Armenian Secret Army for the Liberation of Armenia and the Justice Commandos of the Armenian Genocide." Dynamics of Asymmetric Conflict. 1:231-249

In this paper we examine the trajectories of two Armenian terrorist groups: the Armenian Secret Army for the Liberation of Armenia (ASALA) and the Justice Commandos of the Armenian Genocide (JCAG). Both groups began in the mid-1970s and by the early 1980s had become extremely active. However, shortly afterwards, attacks and fatalities attributed to ASALA and JCAG plummeted and by 1988 both groups had effectively disintegrated. The pivotal historical event in our analysis is an especially brutal attack on Paris's Orly Airport in 1983 which we believe undermined the legitimacy of ASALA among its supporters in the Armenian Diaspora and in the West. We use data from the Global Terrorism Database (GTD) from 1975 to 1988 as well as extensive qualitative evidence to examine these issues. Based on Cox proportional hazard models, we find that both total ASALA attacks and ASALA attacks on non Turkish targets significantly increased until the Orly incident, but significantly decline thereafter. Although JCAG was not involved in the Orly bombing and in general had a much more disciplined approach, JCAG attacks also declined rapidly following Orly. The results suggest that when a terrorist organization depends heavily on a Diaspora, over-reaching in terrorist targeting offers a strong opening for discrediting terrorism as a tactic, even discrediting terrorists who have not over-reached. Journal Website

Kis-Katos, Krisztina, Helge Liebert, and Gunther G. Schulze. Forthcoming. "On the Origin of Domestic and International Terrorism." European Journal of Political Economy.

We analyze the determinants of the origin of domestic and international terrorism in a large panel data set of 159 countries spanning from 1970 to 2007. We show that terror increases with GDP per capita, a higher polity score measuring a more open and competitive political system and experiences of domestic conflict, anarchy and regime transitions. Our evidence thus contradicts the notion that terrorism is rooted in economic deprivation or that strongly autocratic regimes breed more terrorists. Rather we show that weak or failing states are an incubator for terrorism. We also show that the causes of domestic terror and international terror are similar.

Kollias, Christos, Petros Messus, Nikolaos Mylonidis, and Suzanna-Maria Paleologou 2009 "Terrorism and the Effectiveness of security spending in Greece: Policy implications of some empirical findings." Journal of Policy Modeling 31: 788-802

Greece has over the years faced serious security challenges from domestic as well as transnational terrorist activity. This paper examines empirically the effectiveness of counter-terrorism policy and particularly it focuses on current and investment expenditure on domestic security and public order. Using annual budget data for the 1974–2004 period, it investigates whether current and investment spending by the Ministry of Public Order has been an effective policy measure to counter terrorism. The results seem to suggest that such investment has at best a weak negative impact on internal terrorist actions. The main policy implication of this finding is that investing in counter-terrorist infrastructure and equipment can potentially prove to be an effective policy measure in the fight against terrorism. This, however, may be conditional upon a number of other factors including other anti-terrorist measures such as legislation or how efficiently such expenditure is used.

LaFree, Gary. 2009. Criminology’s third war: Special issue on terrorism and responses to terrorism. Criminology and Public Policy 8:431-444.

The editorial introduction of the special issue of Criminology and Public Policy on “Homeland Security and Terrorism” argues that out of the three major crime-related political wars: the war on crime, drugs, and terrorism, academic criminology was far more engaged in the first two than in the third one. However, the relatively small number of criminologists active in terrorism research has begun to change in recent years. The editorial introduces the articles and policy essays included in the special issue. The articles are grounded in empirical data and rely extensively on criminological theories. Finally the editorial argues that although the study of terrorism has started to attract the attention of academic criminology, a greater involvement is required.

LaFree, Gary and Laura Dugan. 2009. Research on terrorism and countering terrorism. In Crime and Justice: A Review of Research, M. Tonry (ed.) Chicago: University of Chicago Press 38: 413-477.

Social and behavioral research on terrorism has expanded dramatically. However, theoretical work that incorporates terrorism and collection of valid data on it has lagged behind theoretical work on other criminological subjects. Theorizing has been dominated by deterrence perspective. Threats of severe consequence for terrorist acts in general show little promise, but there is evidence that increasing the certainty of consequence works in some situations. Research on terrorism will be improved if it moves beyond deterrence to include concepts drawn from legitimacy, strain, and situational perspectives. Limitations of traditional criminology data sources for studying terrorism have encouraged the developments of open-source-event databases. The most comprehensive when this article was being prepared was created by combining the Global Terrorism Database with RAND-MIPT data, documents more than 77,000 terrorist incidents from 1970 to 2006. Attacks peaked in the early 1990s and then declined substantially until 9/11. They have since substantially increased. The regional concentration of terrorism has moved from Western Europe in the 1970s to Latin America in the 1980s, to the Middle East and Persian Gulf in the twenty-first century. Despite the enormous resources devoted to countering terrorism, surprisingly little empirical information is available on which strategies are most effective.

LaFree, Gary, Laura Dugan, and Derrick Franke. 2005. "The Interplay between Terrorism, Nonstate Actors, and Weapons of Mass Destruction: An Exploration of the Pinkerton Database." International Studies Review 7:155-158.

The purpose of this analysis was to provide an exploratory look at a recently computerized database, examining the interplay between nonstate actors, terrorism, and WMD. In this brief overview, we have concentrated on the following risk factors: (1) previous use of WMD, (2) a history of willingness to launch attacks outside of the country of origin, (3) willingness to kill large numbers of people, and (4) attempts to achieve maximum lethality. Along the way, we have identified certain groups that fill these criteria and thus will be candidates for mass impact terrorism in the future. In short, although making no statistically formulated arguments, the data discussed here nonetheless serve as a point of departure for a better understanding of a host of issues of concern in both the academic and policy fields. Journal Website

LaFree, Gary and Laura Dugan. 2007. "Introducing the Global Terrorism Database." Terrorism and Political Violence 19:181-204.

Compared to most types of criminal violence, terrorism poses special data-collection challenges. In response, there has been growing interest in open-source terrorist event data bases. One of the major problems with these data bases in the past is that they have been limited to international events—those involving a national or group of nationals from one country attacking targets physically located in another country. Past research shows that domestic incidents greatly outnumber international incidents. In this paper we describe a previously unavailable open source data base that includes some 70,000 domestic and international incidents since 1970. We began the Global Terrorism Database (GTD) by computerizing data originally collected by the Pinkerton Global Intelligence Service (PGIS). Following computerization, our research team has been working for the past two years to validate and extend the data to real time. In this paper, we describe our data collection efforts, the strengths and weaknesses of open source data in general and the GTD in particular, and provide descriptive statistics on the contents of this new resource. Journal Website

LaFree, Gary, Laura Dugan and Susan Fahey. 2007. "Global Terrorism and Failed States," In Peace and Conflict, J. Joseph Hewitt, Jonathan Wilkenfeld, and Ted Robert Gurr (eds.). Boulder: Paradigm Publishers.

As international concern about terrorism has grown, researchers and policymakers have increasingly sought to understand terrorism by looking at the social, economic, and political characteristics of countries. Lafree, Dugan, and Fahey examine connections between a newly available measure of terrorist attacks-the Global Terrorism Database (GTD) covering the period between 1970 and 1997-and state failure, defined by the Political Instability Task Force as including "civil conflicts, political crises, and massive human rights violations that are typically associated with state breakdown." Book Website

LaFree, Gary and Laura Dugan. 2009. "Tracking Global Terrorism, 1970-2004." In To Protect and to Serve: Police and Policing in an Age of Terrorism, David Weisburd, Thomas Feucht, Idit Hakimi, Lois Mock and Simon Perry (eds.). New York: Springer.

Terrorism is a form of crime. Yet compared to most types of crime, terrorism poses unique data collection challenges. As a result, even basic descriptive questions about terrorism have been difficult or impossible to answer: What are the long term trends in terrorist attacks? Is the number of fatalities associated with terrorist attacks increasing over time? What types of attacks are most common? What types of weapons do terrorists use most frequently? How long do terrorist groups last? In this chapter we analyze newly available data from the Global Terrorism Database (GTD) to provide a descriptive account of more than 82,000 domestic and international terrorist attacks that occurred between 1970 and 2004. We provide detailed information on global and country-level terrorism trends, regional characteristics of terrorism, and characteristics of the major groups that have employed terrorist methods. This chapter is meant to provide an overview of the characteristics of global terrorism. We show that many common stereotypes about terrorism receive little support. To place terrorism in a global political context, we include an analysis that links terrorist attacks to political characteristics of nations concentrating especially on level of democratization and state failures. We also examine how terrorism rates compare to more common forms of crime. We conclude with a discussion about important research questions for the future. Book Website

LaFree, Gary, and Laura Dugan. 2004. How does studying terrorism compare to studying crime? In Mathieu DeFlem (ed.), Criminology and Terrorism. Elsevier.

Although the research literature on terrorism has expanded dramatically since the 1970s, with few exceptions little of this work has been done by criminologists or has appeared in criminology journals. This is surprising because breaking of laws and reactions to the breaking of laws have long been central concerns of criminology and terrorism is closely related to both of these concerns. In this paper we compare crime and terrorism in terms of conceptualization, data collection and methodology. In general we find many similarities and even though there are important conceptual and methodological differences, many of these are similar to the familiar tension that exists between general criminology and specialized areas of study such as organized crime, hate crime or juvenile gangs. In short, we conclude that criminological theory, data collection, and methodological approaches are highly relevant to terrorism research and that applying criminological methods to the study of terrorism could rapidly increase our knowledge of terrorism and our understanding of its causes and consequences.

LaFree, Gary, Laura Dugan and Raven Korte. 2009. "The Impact of British Counter Terrorist Strategies on Political Violence in Northern Ireland: Comparing Deterrence and Backlash Models," Criminology 47:501-530.

Criminologists since Becarria and Bentham have been concerned with predicting how governmental attempts to maintain lawful behavior affect subsequent rates of criminal violence. In this paper we build on prior research to argue that governmental responses to a specific form of criminal violence—terrorism—may produce both a positive deterrence effect (i.e., reducing future incidence of prohibited behavior) but also a negative backlash effect (i.e., increasing future incidence of prohibited behavior). Deterrence-based models have long dominated both criminal justice and counter terrorist policies on responding to violence. They maintain that an individual's prohibited behavior can be altered by the threat and imposition of punishment. By contrast, research on backlash models applied to either criminal justice or counter terrorist policies are less common and more theoretically scattered. Nevertheless, there is substantial support for such arguments from research on counter terrorism, from criminology research on labeling, legitimacy and defiance, and from the psychological literature on social power and decision making. In this paper we identify six major British strategies aimed at reducing political violence in Northern Ireland from 1969 to 1992 and then use Cox proportional hazard models to estimate the impact of these interventions on the risk of new attacks. In general, we find the strongest support for backlash models. The only support for deterrence models was a military surge called Operation Motorman which showed significant declines in the risk of new attacks. The results underscore the importance of considering the possibility that anti-terrorist interventions might increase as well as decrease subsequent violence. Journal Website

LaFree, Gary, Laura Duga, Min Xie, and Piyusah Singh. Forthcoming. "Spatial and Temporal Patterns of Terrorist Attacks by ETA 1970-2007." Journal of Quantitative Criminology.

Rational choice perspectives maintain that seemingly irrational behavior on the part of terrorist organizations may nevertheless reflect strategic planning. In this paper we examine spatial and temporal patterns of terrorist attacks by the Spanish group ETA between 1970 and 2007. Our analysis is guided by a public announcement by ETA in 1978 that the group would shift from emphasizing attacks in the Basque territory to instead launch attacks more widely in the hopes of exhausting the Spanish government and forcing it to abandon the Basque territory. This announcement suggests that prior to the end of 1978 ETA attacks were based mostly on controlling territory in the Basque region that they hoped to rule; and after 1978 the organization decided to instead undertake a prolonged war of attrition. Accordingly, we argue that before the end of 1978 ETA was mostly perpetrating control attacks (attacking only within the Basque territories) and that the diffusion of attacks between provinces was mostly contagious (spreading contiguously). After the 1978 proclamation, we argue that the attack strategy shifted toward attrition (attacking in areas outside of the Basque territories) and that the attacks were more likely to diffuse hierarchically (spreading to more distant locations). As predicted, we find that after ETA moved toward a more attrition based attack strategy, subsequent attacks were significantly more likely to occur outside the Basque region and to target non-adjacent regions (consistent with hierarchical diffusion). We also find that hierarchical diffusion was more common when a longer time elapsed between attacks (a likely consequence of the fact that more distant attacks require more resources and planning) and that attacks against Madrid were unlikely to be followed immediately by more attacks on Madrid or surrounding provinces. After ETA announced a shift in policy, they maintained a highly dispersed attack strategy even during their period of decline. Using information about where and when prior attacks occurred could provide useful information for policy makers countering groups like ETA.

LaFree, Gary, and James Hendrickson. 2007. Build a criminal justice policy for terrorism. Criminology and Public Policy 6:781-790.

With some notable and mostly recent exceptions, criminologists have been slow to study terrorism and responses to terrorism. In this essay, we provide evidence instead for the argument that important policy reasons exist for criminologists to be involved in the fight against terrorism. We consider ways that criminology and criminal justice can be of direct and indirect assistance in the fight against terrorism. Finally we propose that as a science, criminology should play a major role in establishing best practices for the processing of those accused of terrorism and to provide etiological theories and research methods for understanding terrorism.

LaFree, Gary and Erin Miller. 2009. "Desistance from Terrorism: What Can We Learn from Criminology?" Dynamics of Asymmetric Conflict. 1:203-230

In recent years an increasing number of researchers have observed that there are far fewer studies of how terrorism ends than how it begins. In criminology the issue of how crime ends has been shaped by discussions of desistance, the prolonged or permanent cessation of criminal behavior. We begin this essay with a brief review of research on desistance in criminology, considering first the conceptual challenges of desistance research and then reviewing major theoretical frameworks and empirical findings from criminology that might help inform an understanding of desistance from terrorism. We conclude with a discussion of the implications of desistance research in criminology for research on terrorism at the individual- and group-level and identify several objectives for such a research agenda. Journal Website

LaFree, Gary, Nancy Morris and Laura Dugan. 2010. "Cross-National Patterns of Terrorism: Comparing Trajectories for Total, Attributed and Fatal Attacks, 1970 to 2006." British Journal of Criminology 50:622-649.

Despite growing international concern about terrorism, until recently, very little was known about worldwide risk patterns for terrorist attacks. In this paper, we are especially interested in determining the extent to which terrorism is concentrated at the country level over time and whether different measures of terrorism (total, attributed and fatal attacks) yield similar results. Traditional sources of crime data—official police records and victimization and self-report crime surveys—typically exclude terrorism. In response, there has been growing interest in terrorist event databases. In this research, we report on the most comprehensive of these databases to date, formed by merging the Global Terrorism Database maintained by the START Center with the RAND-MIPT database. We use a statistical method called semi-parametric group-based trajectory analysis to examine 73,961 attacks in 206 countries and territories from 1970 to 2006. Our results confirm that terrorist attacks, like more common crimes, are highly concentrated across specific countries and these concentrations are fairly stable over time. Ten countries account for 38 per cent of all terrorist attacks in our data since 1970; 32 countries account for more than three-quarters of all attacks. The trajectory analysis also reveals a rapidly rising new terrorist threat concentrated especially among countries in South and Southeast Asia, the Middle East and Africa.

LaFree, Gary, Nancy Morris, Laura Dugan and Susan Fahey. 2006. "Identifying Global Terrorist Hot Spots." In Tangled Roots: Social and Psychological Factors in the Genesis of Terrorism, ed. Jeffery Victoroff. Amsterdam: IOS Press.

The existence of violent crime hot spots, both in neighborhoods and countries, which remain relatively stable over time, has been fairly well-established in the criminological literature. In this chapter, we ask if terrorism incidents are also concentrated in a relatively few number of countries and whether that concentration has remained stable over time. We use the Global Terrorism Database which includes 70,000 domestic and international terrorism incidents from 1970 to 1997. We use semi-parametric trajectory analysis to estimate and describe long term patterns of terrorism activity for all countries during the time span. In addition, we classify countries with similar patterns into groups which reflect the overall pattern of terrorism. Our results indicate that there are four trajectory groups in the data, each of which represents a distinct pattern of terrorism activity over time. Although the vast majority of countries experience relatively few numbers of terrorist incidents over time, a small percentage of countries account for the majority of terrorist incidents in our data. Moreover, the clustering of incidents at the country level remains stable over time. For example, countries in trajectory group four represent only 8% of countries in the data, however they accounted for 67% of all incidents between 1970 and 1997. We conclude that there is a substantial amount of concentration of terrorist incidents within particular countries, and this concentration is stable over time. This suggests that the policing of terrorism should not be conducted in a random manner; rather resources for combating terrorism ought to be concentrated in the places with the most terrorism. Book Website

LaFree, Gary, Sue-Ming Yang and Martha Crenshaw. 2009. "Trajectories of Terrorism: Attack Patterns of Foreign Groups that have targeted the United States, 1970 to 2004." Criminology and Public Policy 8:445-473.

While researchers began to assemble open-source terrorism event data bases in the late 1960s, until recently most of these data bases excluded domestic attacks. This is a particularly misleading exclusion for the United States: while the United States is often perceived to be the central target of transnational terrorism, the domestic attacks of the foreign groups targeting the United States are often ignored. We begin this paper with 53 foreign terrorist groups that have been identified by U.S. State Department and other government sources as posing a special threat to the United States. Using the Global Terrorism Database that includes both domestic and transnational terrorist attacks, we examine 16,916 attacks attributed to these groups between 1970 and 2004. We find that just over three percent of attacks by these designated anti-U.S. groups were actually directed at the United States. Moreover, 99 percent of the attacks that targeted the United States did not occur on U.S. soil, but were aimed at U.S. targets in other countries (e.g., embassies or multilateral corporations). We also find that over 90 percent of the non-U.S. attacks were domestic (nationals from one country attacking targets of the same nationality in the same country). We use group-based trajectory analysis to examine the different developmental trajectories of U.S. target and non-U.S. target terrorist strikes and conclude that four trajectories best capture attack patterns for both. These trajectories outline three terrorist waves, occurring in the 1970s, 1980s and the early twenty-first century, as well as a trajectory that does not exhibit wave-like characteristics but instead is characterized by irregular and infrequent attacks. Journal Website

Memon, Nasrullah, Uffe Kock Wiil, Reda Alhajj, Claus Atzenbeck, and Nicholas Harkiolakis. 2011 "Harvesting covert networks: A case study of the iMiner database." Int. J. Networking and Virtual Organizatios 8:52-74.

Data collection of covert networks is an inherently difficult task because of the very nature of these networks. Researchers find it difficult to locate and access data relating to the structure and function of such networks in order to study this extreme social phenomenon. In addition, information collected by intelligence agencies and government organizations is inaccessible to researchers. To counter the information scarcity, we designed and built a database of terrorist-related data and information by harvesting such data from publicly available authenticated websites. The database was incorporated in the iMiner prototype tool, which makes use of investigative data mining techniques to analyze data. This paper will present the developed framework along with the form and structure of the terrorist data in the database. Selected cases will be referenced to highlight the effectiveness of the iMiner tool and its applicability to real-life situations.

Piazza, James and James Igoe Walsh 2010 "Physical Integrity Rights and Terrorism" Political Science and Politics 43: 411-414

Can states afford to protect human rights when facing a terrorist threat? Contemporary academic literature suggests that the answer to this question is no, concluding that states that afford their citizens basic political rights and civil liberties leave themselves more exposed to terrorist attacks (Piazza 2008; Wade and Reiter 2007; Pape 2003; Eubank and Weinberg 1994). American policymakers seem to agree. Both the Bush and Obama administrations regard the curtailment of physical integrity rights as a necessary element of effective counterterrorism policy. The Bush administration responded to the terrorist attacks of September 11, 2001, with policies permitting indefinite detention, extraordinary rendition, use of physically abusive interrogation practices, and increased and largely unchecked surveillance and wiretapping of suspected terrorists. Although it banned abusive interrogation and announced plans to close the detention facility at Guantanamo Bay, the Obama administration has maintained the practice of wiretapping, reserved the option of rendition, and dramatically increased unmanned drone attacks against suspected terrorists in Pakistan, which often results in civilian casualties. Both presidents have claimed that these policies are necessary to keep Americans safe from terrorism (Hosenball 2009; "Bush Defends Policy on Terror Detainees" 2005).

Wang, Xiaoyu, Erin Miller, Kathleen Smarick, William Ribarsky, and Remco Chang. 2008. "Investigative Visual Analysis of Global Terrorism." Computer Graphics Forum 27: 919-926.

Recent increases in terrorist activity around the world have made analyzing and understanding such activities more critical than ever. With the help of organizations such as the National Consortium for the Study of Terrorism and Responses to Terrorism (START), we now have detailed historical information on each terrorist event around the world since 1970. However, due to the size and complexity of the data, identifying terrorists' patterns and trends has been difficult. To better enable investigators in understanding terrorist activities, we propose a visual analytical system that focuses on depicting one of the most fundamental concepts in investigative analysis, the five W's (who, what, where, when, and why). Views in our system are highly correlated, and each represents one of the W's. With this approach, an investigator can interactively explore terrorist activities efficiently and discover reasons of attacks (why) by identifying patterns temporally (when), geo-spatially (where), between multiple terrorist groups (who), and across different methods or modes of attacks (what). By coupling a global perspective with the details gleaned from asking these five questions, the system allows analysts to think both tactically and strategically. Journal Article

Webb, Jennifer J., and Susan L. Cutter. 2009. "The Geography of U.S. Terrorist Incidents, 1970-2004." Terrorism & Political Violence 21: 428-449

This paper describes the spatio-temporal trends in terrorist incidents in the United States, from 1970 through 2004. Utilizing the Global Terrorism Database (GTD) and ancillary data, we examine both the frequency of incidents and their characteristics: location, target type, attack type, weapon type, and perpetrator group. While the frequency of terrorist incidents has declined since the 1970s, there still is significant activity nationwide. Instead of urban-rural or West Coast-East Coast divisions, the pattern is a more complex mosaic based on group identity, target, and weapon type. We conclude that there is an explicit geography of terrorism, one that is quite decentralized and highly localized.

Young, Joseph K., and Laura Dugan. 2011. "Veto Players and Terror." Journal of Peace Research 48:19-33.

Democratic regimes have been linked to terrorism for contending reasons, with some scholars claiming democracy increases terrorism and others claiming it decreases terror. Corroborating evidence has been used for both relationships leading to the following puzzle: why do some democratic regimes seem to foster terrorism while others do not? We offer an explanation based on Tsbelis’s veto players theory. Beginning with the assumption that terror groups want to change government policy, we argue that the more veto players present in a political system, the more likely the system is to experience deadlock. Given the inability of societal actors to change policies through nonviolent and institutional participation, these systems will tend to generate more terror events. We also explore different methods for estimating terrorism models. We identify several ways to match the data with the proper statistical estimator and discuss implications for terrorism research. Finally, we use new data from the Global Terrorism Database (GTD) that was previously unavailable. These data allow us to use different operational definitions of terrorism and to identify homegrown terror events.