Nahomi Ichino

Deterring or Displacing Electoral Irregularities? Spillover Effects of Observers in a Randomized Field Experiment in Ghana

This article studies the effect of domestic observers deployed to reduce irregularities in voter registration in a new democracy, and in particular, the response of political parties’ agents to these observers. Because political parties operate over large areas and party agents may relocate away from observed registration centers, observers may displace rather than deter irregularities. We design and implement a large-scale two-level randomized field experiment in Ghana in 2008 taking into account these spillovers and find evidence for substantial irregularities: the registration increase is smaller in constituencies with observers; within these constituencies with observers, the increase is about one-sixth smaller on average in electoral areas with observers than in those without; but some of the deterred registrations appear to be displaced to nearby electoral areas. The finding of positive spillovers has implications for the measurement of electoral irregularities or analysis of data collected by observers.

Crossing the Line: Local Ethnic Geography and Voting in Ghana

Theories of instrumental ethnic voting in new democracies propose that voters support co-ethnic politicians because they expect politicians to favor their co-ethnics once in office. But many goods that politicians deliver to voters are locally nonexcludable in rural areas, so the local presence of an ethnic group associated with a politician should affect a rural voters assessment of how likely she is to benefit from that politicians election. Using geocoded polling-station–level election results alongside survey data from Ghana, we show that otherwise similar voters are less likely to vote for the party of their own ethnic group, and more likely to support a party associated with another group, when the local ethnic geography favors the other group. This result helps account for the imperfect correlation between ethnicity and vote choice in African democracies. More generally, this demonstrates how local community and geographic contexts can modify the information conveyed by ethnicity and influence voter behavior.

Primaries on Demand? Intra-Party Politics and Nominations in Ghana

In new democracies, why do political party leaders relinquish power over nominations and allow legislative candidates to be selected by primary elections? Where the legislature is weak and politics is clientelistic, democratization of candidate selection is driven by local party members seeking benefits from primary contestants. Analysis of an original dataset on legislative nominations and political interference by party leaders for the 2004 and 2008 elections in Ghana shows that primaries are more common where nominations attract more aspirants and where the party is more likely to win, counter to predictions in the existing literature. Moreover, the analysis shows that party leaders interfere in primaries in a pattern consistent with anticipation of party members’ reactions.

Increasing Inferential Leverage in the Comparative Method Placebo Tests in Small-n Research

We delineate the underlying homogeneity assumption, procedural variants, and implications of the comparative method and distinguish this from Mill’s method of difference. We demonstrate that additional units can provide “placebo” tests for the comparative method even if the scope of inference is limited to the two units under comparison. Moreover, such tests may be available even when these units are the most similar pair of units on the control variables with differing values of the independent variable. Small-n analyses using this method should therefore, at a minimum, clearly define the dependent, independent, and control variables so they may be measured for additional units, and specify how the control variables are weighted in defining similarity between units. When these tasks are too difficult, process tracing of a single unit may be a more appropriate method. We illustrate these points with applications to two studies.

Models, methods and network topology: Experimental design for the study of interference

How should a network experiment be designed to achieve high statistical power? Ex- perimental treatments on networks may spread. Randomizing assignment of treatment to nodes enhances learning about the counterfactual causal effects of a social network experiment and also requires new methodology (ex. Aronow and Samii 2017a; Bow- ers et al. 2013; Toulis and Kao 2013). In this paper we show that the way in which a treatment propagates across a social network affects the statistical power of an ex- perimental design. As such, prior information regarding treatment propagation should be incorporated into the experimental design. Our findings justify reconsideration of standard practice in circumstances where units are presumed to be independent even in simple experiments: information about treatment effects is not maximized when we assign half the units to treatment and half to control. We also present an exam- ple in which statistical power depends on the extent to which the network degree of nodes is correlated with treatment assignment probability. We recommend that re- searchers think carefully about the underlying treatment propagation model motivat- ing their study in designing an experiment on a network.