Accounting for Extra-Dyadic Sources of International Outcomes

Leaders consider the broader international landscape when making foreign policy choices. This landscape could encompass a single external actor, the local region, or even the whole international system. Quantitative analyses of international outcomes, however, frequently do not account for this broader context. This study suggests a corrective, illustrating the value of incorporating extra-dyadic variables into analyses with dyadic and monadic outcomes. The challenge is to parsimoniously capture theoretically salient elements of the multilateral environment. We contend that a measure that links distributions of power within any k-set of relevant states to uncertainty over conflict outcomes is a promising option for two reasons. First, the measure builds from and accords with canonical theories of international politics. Second, it offers scholars a simple and flexible means to define and account for the set of states that constitute the relevant multilateral landscape. Illustrative applications linking power distributions and outcome uncertainty to alliance formation and pursuit of nuclear weapons demonstrate that extra-dyadic factors consistently influence foreign policy outcomes. This study thus shows that situating such outcomes within their broader context is both feasible and substantively important. Moreover, it contributes to recent efforts to address shortcomings of monadic and dyadic studies.