A Scalable MCEM Estimator for Spatio-Temporal Autoregressive Models

Very large spatio-temporal lattice data are becoming increasingly common across a variety of disciplines. However, estimating interdependence across space and time in large areal datasets remains challenging, as existing approaches are often (i) not scalable, (ii) designed for conditionally Gaussian outcome data, or (iii) are limited to cross-sectional and univariate outcomes. This paper proposes an MCEM estimation strategy for a family of latent-Gaussian multivariate spatio-temporal models that addresses these issues. The proposed estimator is applicable to a wide range of non-Gaussian outcomes, and implementations for binary and count outcomes are discussed explicitly. The methodology is illustrated on simulated data, as well as on weekly data of IS-related events in Syrian districts.Comment: 29 pages, 8 figure

Estimating Interdependence Across Space, Time and Outcomes in Binary Choice Models Using Pseudo Maximum Likelihood Estimators

Binary outcome models are frequently used in Political Science. However, such models have proven particularly dicult in dealing with interdependent data structures, including spatial autocorrelation, temporal autocorrelation, as well as simultaneity arising from endogenous binary regressors. In each of these cases, the primary source of the estimation challenge is the fact that jointly determined error terms in the reduced-form specication are analytically intractable due to a high-dimensional integral. To deal with this problem, simulation approaches have been proposed, but these are computationally intensive and impractical for datasets with thousands of observations. As a way forward, in this paper we demonstrate how to reduce the computational burder signicantly by (i) introducing analytically tractable pseudo maximum likelihoodestimators for latent binary choice models that exhibit interdependence across space, time and/or outcomes, and by (ii) proposing an implementation strategy that increases computational eciency considerably. Monte-Carlo experiments demonstrate that our estimators perform similarly to existing alternatives in terms of error, but require only a fraction of the computational cost

Polygyny or Misogyny? Reexamining the “First Law of Intergroup Conflict”

Kanazawa (2009) proposes a "first law of intergroup conflict," suggesting that polygyny and its impact on access to reproductive women provides "the ultimate cause" for civil war. This controversial claim is supported by an empirical analysis at odds with most existing studies of civil wars. We reconsider the influence of polygyny in a more conventional statistical model. We fail to find evidence that ethnic groups with polygyny engage more frequently in civil wars, although it is possible to find results indicating that civil wars may be more common in states with legal polygamy. We detail how these findings seem at odds with Kanazawa's theory and argue that misogyny seems a more plausible source of insights into the context for civil war and peace. We then show that civil wars are less common when women's rights are better established and that legal polygamy has no discernable residual effect once women's rights are considered. © 2011 Southern Political Science Association

Ethnicity, the State, and the Duration of Civil War

Previous research has focused primarily on how ethnicity may trigger civil war, and its effect on conflict duration remains disputed. Rather than treating conflict as a direct consequence of ethnic cleavages, the authors argue that ethnicity per se does not affect civil war duration. Instead, its effect depends on its relationship to political institutions. They employ a dyadic approach that emphasizes the political context in which both government leaders and nonstate challengers can capitalize on the ascriptive nature of ethnicity. They show that although states can initially benefit from politicizing ethnic relations, once violent conflict breaks out, such policies may backfire on the government and make it difficult for incumbent governments to accept settlements that could terminate conflicts. Past policies of ethnic exclusion also benefit rebel organizations fighting the government, since the resulting grievances increase collective group solidarity and render individual fighters more cost tolerant. Using a new data set that codes the nexus between rebel organizations and ethnic groups, as well as information on ethnopolitical exclusion, the authors find considerable support for their propositions.</jats:p

The Diffusion of Inclusion: An Open Polity Model of Ethnic Power Sharing

While there is a growing consensus that ethnic inclusion produces peace, less is known about what causes transitions to power sharing between ethnic groups in central governments in multiethnic states. The few studies that have addressed this question have proposed explanations stressing exclusively domestic factors. Yet, power sharing is spatially clustered, which suggests that diffusion may be at play. Inspired by studies of democratic diffusion, we study the spread of inclusive policies with an “open polity model” that explicitly traces diffusion from inclusion in other states. Our findings indicate that the relevant diffusion processes operate primarily at the level of world regions rather than globally or between territorial neighbors. Thus, the more inclusive the region, the more likely a shift to power sharing becomes. Shifts away from inclusion to dominance are less common since World War II, but they are more likely in regional settings characterized by ethnic exclusion

Modernization and Democracy: Theories and Evidence Revisited.

We review the literature on the relation between socio-economic development and political democracy, a field that is commonly known as modernization theory. Guided by the seminal contribution of Lipset (1959), we assess the evolution of this literature along two major dimensions: (1) robustness of the relationship between economic development and democracy and (2) substantiation of the causal mechanism. The evidence to date suggests that Lipset&apos;s original thesis does indeed find empirical support, and that certain structural conditions are conducive to stable democracy

Trojan Horse, Copycat, or Scapegoat? Unpacking the Refugees-Terrorism Nexus

Widespread fear that hosting refugees will mean more terrorism in host states is at theheart of the ‘refugee crisis’. Yet, we lack rigorous evidence for such claims. This articletheoretically unpacks how and under what conditions transnational refugee movementsplausibly lead to different types of terrorist outcomes. Combining original data witha multi-pronged approach involving a treatment-placebo design as well as instrumentalvariable estimation, we provide systematic and robust evidence that sheds new light onthe security implications of transnational forced migration. Our findings challenge theclaim that hosting refugees heightens the risk of “importing” terrorist attacks againstnationals of host countries, especially in developed countries. However, in these coun-tries refugees themselves are particularly prone to becoming the targets of retaliatoryterrorist attacks by natives, driven by fear. Dominant policy responses to the refugeecrisis that raise fears and suspicions are therefore not only ill-suited, but potentiallycounterproductive