1 July 7, 2010, marks the fifth anniversary of the 2005 terrorist attacks on London’s Metro system. In 2005, terrorists launched a coordinated attack against London’s transportation system, with 3 bombs detonating simultaneously at three different Metro stations and a fourth bomb exploding an hour later on a city bus. In all, there were 52 victims in these bombings with an additional 700 injuries resulting. The four terrorists who executed the attacks were killed in the explosions.

National Consortium for the Study of Terrorism and Responses to Terrorism

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.

Domestic versus transnational terrorism: Data, decomposition, and dynamics

This book argues that political and economic inequalities following group lines generate grievances that in turn can motivate civil war. Lars-Erik Cederman, Kristian Skrede Gleditsch, and Halvard Buhaug offer a theoretical approach that highlights ethnonationalism and how the relationship between group identities and inequalities are fundamental for successful mobilization to resort to violence. Although previous research highlighted grievances as a key motivation for political violence, contemporary research on civil war has largely dismissed grievances as irrelevant, emphasizing instead the role of opportunities. This book shows that the alleged non-results for grievances in previous research stemmed primarily from atheoretical measures, typically based on individual data. The authors develop new indicators of political and economic exclusion at the group level, and show that these exert strong effects on the risk of civil war. They provide new analyses of the effects of transnational ethnic links and the duration of civil wars, and extended case discussions illustrating causal mechanisms.

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Inequality, Grievances, and Civil War

Difference-in-differences (DID) is commonly used for causal inference in time-series cross-sectional data. It requires the assumption that the average outcomes of treated and control units would have followed parallel paths in the absence of treatment. In this paper, we propose a method that not only relaxes this often-violated assumption, but also unifies the synthetic control method (Abadie, Diamond, and Hainmueller 2010) with linear fixed effects models under a simple framework, of which DID is a special case. It imputes counterfactuals for each treated unit using control group information based on a linear interactive fixed effects model that incorporates unit-specific intercepts interacted with time-varying coefficients. This method has several advantages. First, it allows the treatment to be correlated with unobserved unit and time heterogeneities under reasonable modeling assumptions. Second, it generalizes the synthetic control method to the case of multiple treated units and variable treatment periods, and improves efficiency and interpretability. Third, with a built-in cross-validation procedure, it avoids specification searches and thus is easy to implement. An empirical example of Election Day Registration and voter turnout in the United States is provided.

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Generalized Synthetic Control Method: Causal Inference with Interactive Fixed Effects Models

Recognizing that the empirical literature of the past several years has produced an inconclusive picture, this study revisits the relationship between poverty and terrorism and suggests a new factor to explain patterns of domestic terrorism: minority economic discrimination. Central to this study is the argument that because terrorism is not a mass phenomenon but rather is undertaken by politically marginal actors with often narrow constituencies, the economic status of subnational groups is a crucial potential predictor of attacks. Using data from the Minorities at Risk project, I determine that countries featuring minority group economic discrimination are significantly more likely to experience domestic terrorist attacks, whereas countries lacking minority groups or whose minorities do not face discrimination are significantly less likely to experience terrorism. I also find minority economic discrimination to be a strong and substantive predictor of domestic terrorism vis-a-vis the general level of ec...

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Poverty, minority economic discrimination, and domestic terrorism

This paper quantifies the impact of terrorism and conflicts on income per capita growth in Asia for 1970–2004. Our panel estimations show that transnational terrorist attacks had a significant growth-limiting effect. An additional terrorist incident per million persons reduces gross domestic product per capita growth by about 1.5%. In populous countries, many additional attacks are needed to achieve such a large impact. Transnational terrorism reduces growth by crowding-in government expenditures. Unlike developing countries, developed countries are able to absorb terrorism without displaying adverse economic consequences. An internal conflict has the greatest growth concern, more than twice that of transnational terrorism. Conflict variables are associated with smaller investment shares and increased government spending, with the crowding-in of government spending being the dominant influence.

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The impact of terrorism and conflicts on growth in asia

SUMMARY
This paper presents panel estimates for 18 Western Europe countries to ascertain the separate impacts of domestic and transnational terrorism on income per capita growth for 1971–2004. The paper merges domestic and transnational terrorist events in order to attribute growth impacts to the two broad categories of terrorism. Each additional transnational terrorist incident per million persons reduces economic growth by about 0.4 percentage points. Domestic terrorism has a much smaller effect on growth that is about half this size. Terrorism's negative impact on growth is related to the scale of terrorism in the sample countries in order to give a better idea of what is the average consequence in most sample countries. These negative impacts are shown to stem from domestic and transnational terrorism's adverse influence on investment shares. Counterterrorism efforts also augment government spending, which crowds out growth-promoting investment. We show that the pathway by which domestic and transnational terrorism influences growth differs. For example, transnational terrorism works more through the crowding out of investment, while domestic terrorism works more through the increase in government expenditure increases. A host of sensitivity tests are performed to support our empirical model. Policy recommendations conclude the paper – e.g., measures to curb transnational terrorist attacks have a higher economic payoff than similar measures to reduce domestic terrorist events. Since transnational terrorism has a larger impact on income per capita growth than does domestic terrorism, West European efforts to curb transnational terrorism will have a greater economic dividend than efforts to limit domestic terrorism.

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Growth Consequences of Terrorism in Western Europe

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 (spati...

The Adverse Effect of Transnational and Domestic Terrorism on Growth in Africa

This overview examines critically the post-9/11 empirical literature on terrorism. Major contributions by both economists and political scientists are included. We focus on five main themes: the changing nature of terrorism, the organization of terrorist groups, the effectiveness of counterterrorism policies, modern drivers or causes of terrorism, and the economic consequences of terrorism. In so doing, we investigate a host of questions that include: How do terrorist groups attract and retain members? What determines the survival of terrorist groups? Is poverty a root cause of terrorism? What counterterrorism measures work best? In the latter regard, we find that many counterterrorism policies have unintended negative consequences owing to attack transference and terrorist backlash. This suggests the need for novel policies such as service provision to counter some terrorist groups' efforts to provide such services. Despite terrorists' concerted efforts to damage targeted countries' economies, the empirical literature shows that terrorism has had little or no effect on economic growth or GDP except in small terrorism-plagued countries. At the sectoral level, terrorism can adversely affect tourism and foreign direct investment, but these effects are rather transient and create transference of activities to other sectors, thus cushioning the consequences.

https://www.aeaweb.org/articles/pdf/doi/10.1257/jel.20181444

Khusrav Gaibulloev

Papers

Domestic versus transnational terrorism: Data, decomposition, and dynamics

The impact of terrorism and conflicts on growth in asia

Growth Consequences of Terrorism in Western Europe

The Adverse Effect of Transnational and Domestic Terrorism on Growth in Africa

What We Have Learned about Terrorism since 9/11