Macartan Humphreys

Promoting an open research culture

Author guidelines for journals could help to promote transparency, openness, and reproducibility Transparency, openness, and reproducibility are readily recognized as vital features of science (1, 2). When asked, most scientists embrace these features as disciplinary norms and values (3). Therefore, one might expect that these valued features would be routine in daily practice. Yet, a growing body of evidence suggests that this is not the case (4–6).

Natural Resources, Conflict, and Conflict Resolution: Uncovering the Mechanisms

The interpretation of the resource-conflict link that has become most publicized—the rebel greed hypothesis—depends on just one of many plausible mechanisms that could underlie a relationship between resource dependence and violence. The author catalogues a large range of rival possible mechanisms, highlights a set of techniques that may be used to identify these mechanisms, and begins to employ these techniques to distinguish between rival accounts of the resource-conflict linkages. The author uses finer natural resource data than has been used in the past, gathering and presenting new data on oil and diamonds production and on oil stocks. The author finds evidence that (1) conflict onset is more responsive to the impacts of past natural resource production than to the potential for future production, supporting a weak states mechanism rather than a rebel greed mechanism; (2) the impact of natural resources on conflict cannot easily be attributed entirely to the weak states mechanism, and in particular, the impact of natural resources is independent of state strength; (3) the link between primary commodities and conflict is driven in part by agricultural dependence rather than by natural resources more narrowly defined, a finding consistent with a “sparse networks” mechanism; (4) natural resources are associated with shorter wars, and natural resource wars are more likely to end with military victory for one side than other wars. This is consistent with evidence that external actors have incentives to work to bring wars to a close when natural resource supplies are threatened. The author finds no evidence that resources are associated with particular difficulties in negotiating ends to conflicts, contrary to arguments that loot-seeking rebels aim to prolong wars.

Why Does Ethnic Diversity Undermine Public Goods Provision

A large and growing literature links high levels of ethnic diversity to low levels of public goods provision. Yet although the empirical connection between ethnic heterogeneity and the underprovision of public goods is widely accepted, there is little consensus on the specific mechanisms through which this relationship operates. We identify three families of mechanisms that link diversity to public goods provision—what we term “preferences,” “technology,” and “strategy selection” mechanisms—and run a series of experimental games that permit us to compare the explanatory power of distinct mechanisms within each of these three families. Results from games conducted with a random sample of 300 subjects from a slum neighborhood of Kampala, Uganda, suggest that successful public goods provision in homogenous ethnic communities can be attributed to a strategy selection mechanism: in similar settings, co-ethnics play cooperative equilibria, whereas non-co-ethnics do not. In addition, we find evidence for a technology mechanism: co-ethnics are more closely linked on social networks and thus plausibly better able to support cooperation through the threat of social sanction. We find no evidence for prominent preference mechanisms that emphasize the commonality of tastes within ethnic groups or a greater degree of altruism toward co-ethnics, and only weak evidence for technology mechanisms that focus on the impact of shared ethnicity on the productivity of teams.

Handling and Manhandling Civilians in Civil War

The toll of civil conflict is largely borne by civilian populations, as warring factions target non-combatants through campaigns of violence. But significant variation exists in the extent to which warring groups abuse the civilian population: across conflicts, across groups, and within countries geographically and over time. Using a new dataset on fighting groups in Sierra Leone, this article analyzes the determinants of the tactics, strategies, and behaviors that warring factions employ in their relationships with noncombatants. We first describe a simple logic of extraction which we use to generate hypotheses about variation in levels of abuse across fighting units. We then show that the most important determinants of civilian abuse are internal to the structure of the faction. High levels of abuse are exhibited by warring factions that are unable to police the behavior of their members because they are more ethnically fragmented, rely on material incentives to recruit participants, and lack mechanisms for punishing indiscipline. Explanations that emphasize the importance of local community ties and contestation do not find strong support in the data.

Demobilization and Reintegration

Since 1989, international efforts to end protracted conflicts have included sustained investments in the disarmament, demobilization, and reintegration (DDR) of combatants. Yet while policy analysts have debated the factors that contribute to successful DDR programs and scholars have reasoned about the macro conditions that facilitate successful peace building, little is known about the factors that account for successful reintegration at the micro level. Using a new dataset of ex-combatants in Sierra Leone, this article analyzes the individual-level determinants of demobilization and reintegration. Past participation in an abusive military faction is the strongest predictor of difficulty in achieving social reintegration. On economic and political reintegration, we find that wealthier and more educated combatants face greater difficulties. Ideologues, men, and younger fighters are the most likely to retain strong ties to their factions. Most important, we find little evidence at the micro level that internationally funded programs facilitate demobilization and reintegration.

Promoting Transparency in Social Science Research

Social scientists should adopt higher transparency standards to improve the quality and credibility of research. There is growing appreciation for the advantages of experimentation in the social sciences. Policy-relevant claims that in the past were backed by theoretical arguments and inconclusive correlations are now being investigated using more credible methods. Changes have been particularly pronounced in development economics, where hundreds of randomized trials have been carried out over the last decade. When experimentation is difficult or impossible, researchers are using quasi-experimental designs. Governments and advocacy groups display a growing appetite for evidence-based policy-making. In 2005, Mexico established an independent government agency to rigorously evaluate social programs, and in 2012, the U.S. Office of Management and Budget advised federal agencies to present evidence from randomized program evaluations in budget requests (1, 2).

The Role of Leaders in Democratic Deliberations: Results from a Field Experiment in São Tomé and Príncipe

Despite a widespread trend toward the adoption of increasingly participatory approaches to political decision making in developing countries, there is little or no evidence that these practices in fact return the benefits attributed to them. This article investigates one specific worry—that participatory decision-making processes may be vulnerable to manipulation by elites. The authors report on a field experiment, drawing on a unique nationwide experiment in democratic deliberation in São Tomé and Príncipe in which the discussion leaders were randomly assigned across meetings. The randomization procedure provides a rare opportunity to identify the impact of leaders on the outcomes of group deliberations. They find that leader effects were extremely large, in many cases accounting for over one-third of all variation in the outcomes of the national discussions. These results have important implications for the design of such deliberative practices. While the total effect of leadership cannot be assessed, it may still be possible to observe when leader influence occurs and to correct for leader effects in comparisons of outcomes across deliberations.

SCIENTIFIC STANDARDS. Promoting an open research culture.

Author guidelines for journals could help to promote transparency, openness, and reproducibility Transparency, openness, and reproducibility are readily recognized as vital features of science (1, 2). When asked, most scientists embrace these features as disciplinary norms and values (3). Therefore, one might expect that these valued features would be routine in daily practice. Yet, a growing body of evidence suggests that this is not the case (4–6).

Promoting an open research culture: Author guidelines for journals could help to promote transparency, openness, and reproducibility

Author guidelines for journals could help to promote transparency, openness, and reproducibility Transparency, openness, and reproducibility are readily recognized as vital features of science (1, 2). When asked, most scientists embrace these features as disciplinary norms and values (3). Therefore, one might expect that these valued features would be routine in daily practice. Yet, a growing body of evidence suggests that this is not the case (4–6).

Spatial Models, Cognitive Metrics, and Majority Rule Equilibria

Long-standing results demonstrate that, if policy choices are defined in spaces with more than one dimension, majority-rule equilibrium fails to exist for a general class of smooth preference profiles. This article shows that if agents perceive political similarity and difference in ‘city block’ terms, then the dimension-by-dimension median can be a majority-rule equilibrium even in spaces with an arbitrarily large number of dimensions and it provides necessary and sufficient conditions for the existence of such an equilibrium. This is important because city block preferences accord more closely with empirical research on human perception than do many smooth preferences. It implies that, if empirical research findings on human perceptions of similarity and difference extend also to perceptions of political similarity and difference, then the possibility of equilibrium under majority rule re-emerges.