"Identifying causal effects attributable to network membership is a key challenge in empirical studies of social networks. In this article, we examine the consequences of endogeneity for inferences about the effects of networks on network members’ behavior. Using the House office lottery (in which newly elected members select their office spaces in a randomly chosen order) as an instrumental variable to estimate the causal impact of legislative networks on roll call behavior and cosponsorship decisions in the 105th–112th Houses, we find no evidence that office proximity affects patterns of legislative behavior. These results contrast with decades of congressional scholarship and recent empirical studies. Our analysis demonstrates the importance of accounting for selection processes and omitted variables in estimating the causal impact of networks."

"Regime transitions are contagious according to the diffusion-of-democracy literature: a country's regime is affected by others' through various predefined networks (e.g. geographical proximity), as well as by the country's own political, economic and social attributes (e.g. GDP levels). My account departs from the existing diffusion theory by allowing for countries' self-selection into peer regime networks based on their democracy levels in the past. For example, a country can form stronger dependency ties with countries that demonstrated similar democracy levels in the past (homophily). In the longitudinal setting, the traditional diffusion mechanism with the presence of self-selection generates the "co-evolutionary dynamic" between country networks and democracy levels. With this recursive feedback process between tie formation and democracy levels, it becomes extremely difficult to evaluate empirically how each country's level of democracy is determined, because we need to distinguish the following three processes statistically. First, country-specific attributes determine the level of democracy as in the earliest democratization studies. Second, other states' democracy levels also predict a country's regime as demonstrated in the conventional diffusion studies. Finally with my theory of endogenous network formation, the seeming diffusion effect is partially a consequence of their self-selection into peer networks. A newer spatial econometric model, an "M-STAR + Co-Evolution" model, is one of the first that allows us to test for all of these three dynamics behind democratization. In my first-cut analysis, I find that all three processes indeed exist."

ETA: It's good to recognize the problem exists, but the model used here does not make it go away, and still fails to identify the influence effect (if one exists).

"Social scientists have sketched four distinct theories to explain a phenomenon that appears to have ramped up in recent years, the diffusion of policies across countries. Constructivists trace policy norms to expert epistemic communities and international organizations, who define economic progress and human rights. Coercion theorists point to powerful nation-states, and international financial institutions, that threaten sanctions or promise aid in return for fiscal conservatism, free trade, etc. Competition theorists argue that countries compete to attract investment and to sell exports by lowering the cost of doing business, reducing constraints on investment, or reducing tariff barriers in the hope of reciprocity. Learning theorists suggest that countries learn from their own experiences and, as well, from the policy experiments of their peers. We review the large body of research from sociologists and political scientists, as well as the growing body of work from economists and psychologists, pointing to the diverse mechanisms that are theorized and to promising avenues for distinguishing among causal mechanisms."

"Civil wars cluster in space as well as time. In this study, we develop and evaluate empirically alternative explanations for this observed clustering. We consider whether the spatial pattern of intrastate conflict simply stems from a similar distribution of relevant country attributes or whether conflicts indeed constitute a threat to other proximate states. Our results strongly suggest that there is a genuine neighborhood effect of armed conflict, over and beyond what individual country characteristics can account for. We then examine whether the risk of contagion depends on the degree of exposure to proximate conflicts. Contrary to common expectations, this appears not to be the case. Rather, we find that conflict is more likely when there are ethnic ties to groups in a neighboring conflict and that contagion is primarily a feature of separatist conflicts. This suggests that transnational ethnic linkages constitute a central mechanism of conflict contagion."

"In this article, the authors focus attention on a poorly understood aspect of contentious politics: the interaction between the transnational diffusion of new forms of protest behavior and police practices in response to them. Studies of diffusion are usually limited to the diffusion of one kind of innovation by one set of actors to another, as in the diffusion of technical innovations from innovators to adopters. But collective action diffusion also produces a parallel and interactive sequence of “public order” reactions. Using the transnational countersummits that emerged around the turn of the century as their source of evidence, the authors focus on the coevolution of protester and police innovations across national boundaries. The authors’ major finding is that the mechanisms that cause protester and police innovations to diffuse are remarkably similar, even though they can combine in different ways at different moments: promotion, the proactive intervention by a sender actor aimed at deliberate diffusion of an innovation; assessment, the analysis of information on past events and their definition as successes or failures, which leads to adaption of the innovation to new sites and situations; and theorization, the location of technical innovations within broader normative and cognitive frameworks. The authors close with a speculative application of their findings to the recent diffusion of protester tactics and regime responses in the Middle East and North Africa."

"[International political economy] should transition to “third wave” scholarship. This transition is necessary because the approach that dominates current American IPE scholarship, Open Economy Politics (OEP), generates inaccurate knowledge. OEP produces inaccurate knowledge because it studies domestic politics in isolation from international or macro processes. This methodological reductionism is often inappropriate for the phenomena IPE studies because governments inhabit a system. As a result, the political choices that OEP attempts to explain are typically a product of the interplay between domestic politics and macro processes. When OEP omits causally significant macro processes from empirical models, the models yield biased inferences about the domestic political relationships under investigation. Although we tolerated such errors when the gains from OEP were large, these errors are less tolerable now that OEP has matured. Consequently, the field should transition toward research that is non-reductionist (systemic), problem-driven, and pluralistic."

--- I don't see how the issue is _reductionism_ so much as _ignoring interactions_.

"This paper examines the diffusion of protest tactics between social movement organizations (SMOs). Drawing on organizational learning theory, we argue that knowledge about specific tactics diffuses between social movement organizations via their co-engagement in protest events. Using a longitudinal network dataset of organizations and their participation in protest events between 1960 and 1995, we adapt novel methodological techniques for dealing with selection and measurement bias in networks analysis, which comes in two forms—1) the mechanism that renders some organizations more likely to select into collaborations than others, and 2) the notion that tactical diffusion is not a result of collaboration, but rather is an artifact of homophily or some form of indirect learning. We find that collaboration is indeed an important channel of tactical diffusion. We also find that SMOs with broader tactical repertoires are more likely to adopt additional tactics as a result of their collaborations with other SMOs, but only up to a point, beyond which such SMOs are spread too thin. Engaging in more collaborations also makes SMOs both more active transmitters and adopters of novel tactics. Finally, achieving some initial overlap in their respective tactical repertoires facilitates the diffusion of tactics between collaborating SMOs."

-- Andrew and I are cited, but they show no real awareness of the fact that Aral's matching method does nothing about latent homophily, and so their results are still completely exposed to confounding (unless they've got truly well-chosen control variables going into the matching).

"It is widely recognized that social movements may spread – or "diffuse" – from one site to another. Such diffusion, however, is a complex and multidimensional process that involves different actors, networks, and mechanisms. This complexity has spawned a large body of literature on different aspects of the diffusion process, yet a comprehensive framework remains an elusive target. This book is a response to that need, and its framework focuses on three basic analytical questions. First, what is being diffused? This question directs attention to both the protest repertoires and interpretive frames that actors construct to define issues and mobilize political claims. Second, how does diffusion occur? This book focuses attention on the activist networks and communication channels that facilitate diffusion, including dialogue, rumors, the mass media, the internet, NGOs, and organizational brokers. Finally, what is the impact of diffusion on organizational development and shifts in the scale of contentious politics? This volume suggests that diffusion is not a simple matter of political contagion or imitation; rather, it is a creative and strategic process marked by political learning, adaptation, and innovation."

"In examining the discussion of social and political phenomena like regime transition, conflict, and policy change, scholars routinely make choices about how proximity is defined and which neighbors should be considered more important than others. Since each specification offers an alternative view of the networks through which discussion can take place, one's decision can exert a significant influence on the magnitude and scope of estimated discussion effects. This problem is widely recognized, but is rarely the subject of direct analysis. In international relations research, connectivity choices are usually ad hoc, driven more by data availability than by theoretically informed decision criteria. We take a closer look at the assumptions behind these choices, and propose a more systematic method to asses the structural similarity of two or more alternative networks, and select one that most plausibly relates theory to empirics. We apply this method to the spread of democratic regime change, and offer an illustrative example of how neighbor choices might impact predictions and inferences in the case of the 2011 Arab Spring."

"Why do very different countries often emulate the same policy model? Two years after Ronald Reagan's income-tax simplification of 1986, Brazil adopted a similar reform even though it threatened to exacerbate income disparity and jeopardize state revenues. And Chile's pension privatization of the early 1980s has spread throughout Latin America and beyond even though many poor countries that have privatized their social security systems, including Bolivia and El Salvador, lack some of the preconditions necessary to do so successfully.

In a major step beyond conventional rational-choice accounts of policy decision-making, this book demonstrates that bounded--not full--rationality drives the spread of innovations across countries. When seeking solutions to domestic problems, decision-makers often consider foreign models, sometimes promoted by development institutions like the World Bank. But, as Kurt Weyland argues, policymakers apply inferential shortcuts at the risk of distortions and biases. Through an in-depth analysis of pension and health reform in Bolivia, Brazil, Costa Rica, El Salvador, and Peru, Weyland demonstrates that decision-makers are captivated by neat, bold, cognitively available models. And rather than thoroughly assessing the costs and benefits of external models, they draw excessively firm conclusions from limited data and overextrapolate from spurts of success or failure. Indications of initial success can thus trigger an upsurge of policy diffusion."

Of course, saying "we assume that correlated effects are absent" is, in this context at least, very much a "we assume we have a can opener" move.

Well, their power law estimation is bad, of course, but more to the point I don't think they're really dealing with an interesting version of the thesis they set out to undermine. (At the very least: even if geography was irrelevant for Internet users, the latter are not uniformly distributed geographically.) The pictures of the diffusion of baby names are cool, though.

" However, for “complex contagions,” such as social movements, collective behaviors, and cultural and social norms, multiple reinforcing ties are needed to support the spread of a behavior diffusion. I show that scale-free networks are much less robust than exponential networks for the spread of complex contagions, which highlights the value of more homogenously distributed social networks for the robust transmission of collective behavior."

Hah!

(But at the same time, getting scooped does not feel good.)