Political scientists frequently use instrumental variables (IV) estimation to estimate the causal effect of an endogenous treatment variable. However, when the treatment effect is heterogeneous, this estimation strategy only recovers the local average treatment effect (LATE). The LATE is an average treatment effect (ATE) for a subset of the population: units that receive treatment if and only if they are induced by an exogenous IV. However, researchers may instead be interested in the ATE for the entire population of interest. In this article, we develop a simple reweighting method for estimating the ATE, shedding light on the identification challenge posed in moving from the LATE to the ATE. We apply our method to two published experiments in political science in which we demonstrate that the LATE has the potential to substantively differ from the ATE.

Does foreign aid improve human rights and democracy? We help arbitrate the debate over this question by leveraging a novel source of exogeneity: the rotating presidency of the Council of the European Union. We find that when a country's former colonizer holds the presidency of the Council of the European Union during the budget-making process, the country is allocated considerably more foreign aid than are countries whose former colonizer does not hold the presidency. Using instrumental variables estimation, we demonstrate that this aid has positive effects on human rights and democracy, although the effects are short-lived after the shock to aid dissipates. We adduce the timing of events, qualitative evidence, and theoretical insights to argue that the conditionality associated with an increased aid commitment is responsible for the positive effects in the domains of human rights and democracy.

T his paper argues that the benefits of international institutions accrue disproportionately to pairs of states that find cooperation most difficult. It determines which states achieve the greatest gains from these institutions by identifying a central reason that states fail to cooperate in international relations: they fear being "held up" by other states for political concessions. Political hold-up problems occur when one state fails to undertake an otherwise productive investment due to the increased ability it would give another state to extract political concessions. Focusing on the World Trade Organization (WTO), I demonstrate that political hold-up problems are pervasive in international relations due to links between economic and political policies, but that international institutions can solve hold-up problems by helping to enforce agreements. I first formalize this argument and then empirically test the implications derived from the model, finding that the WTO increases trade most for politically dissimilar states by reducing states' abilities to hold up their trading partners for foreign policy concessions. I provide evidence of the causal mechanism by showing that WTO membership increases trade in contract-intensive goods and boosts fixed capital investment. I conclude that by solving political hold-up problems, international institutions can normalize relations between politically asymmetric states that differ in terms of capabilities, regime types, and alliances.

Scholars have long argued that international organizations solve information problems through increased transparency. This article introduces a distinct problem that instead requires such institutions to keep information secret. We argue that states often seek to reveal intelligence about other states' violations of international rules and laws but are deterred by concerns about revealing the sources and methods used to collect it. Properly equipped international organizations, however, can mitigate these dilemmas by analyzing and acting on sensitive information while protecting it from wide dissemination. Using new data on intelligence disclosures to the International Atomic Energy Agency and an analysis of the full universe of nuclear proliferation cases, we demonstrate that strengthening the agency's intelligence protection capabilities led to greater intelligence sharing and fewer suspected nuclear facilities. However, our theory suggests that this solution gives informed states a subtle form of influence and is in tension with the normative goal of international transparency.