Matthew Blackwell

The Political Legacy of American Slavery

We show that contemporary differences in political attitudes across counties in the American South trace their origins to slaverys prevalence more than 150 years ago. Whites who currently live in Southern counties that had high shares of slaves in 1860 are more likely to identify as a Republican, oppose affirmative action policies, and express racial resentment and colder feelings toward blacks. These results cannot be explained by existing theories, including the theory of racial threat. To explain these results, we offer evidence for a new theory involving the historical persistence of racial attitudes. We argue that, following the Civil War, Southern whites faced political and economic incentives to reinforce racist norms and institutions. This produced racially conservative political attitudes, which in turn have been passed down locally across generations. Our results challenge the interpretation of a vast literature on racial attitudes in the American South.

A Unified Approach to Measurement Error and Missing Data: Overview and Applications

Although social scientists devote considerable effort to mitigating measurement error during data collection, they often ignore the issue during data analysis. And although many statistical methods have been proposed for reducing measurement error-induced biases, few have been widely used because of implausible assumptions, high levels of model dependence, difficult computation, or inapplicability with multiple mismeasured variables. We develop an easy-to-use alternative without these problems; it generalizes the popular multiple imputation (MI) framework by treating missing data problems as a limiting special case of extreme measurement error and corrects for both. Like MI, the proposed framework is a simple two-step procedure, so that in the second step researchers can use whatever statistical method they would have if there had been no problem in the first place. We also offer empirical illustrations, open source software that implements all the methods described herein, and a companion article with technical details and extensions.

Explaining Causal Findings without Bias: Detecting and Assessing Direct Effects

Researchers seeking to establish causal relationships frequently control for variables on the purported causal pathway, checking whether the original treatment effect then disappears. Unfortunately, this common approach may lead to biased estimates. In this article, we show that the bias can be avoided by focusing on a quantity of interest called the controlled direct effect. Under certain conditions, the controlled direct effect enables researchers to rule out competing explanations—an important objective for political scientists. To estimate the controlled direct effect without bias, we describe an easy-to-implement estimation strategy from the biostatistics literature. We extend this approach by deriving a consistent variance estimator and demonstrating how to conduct a sensitivity analysis. Two examples—one on ethnic fractionalization’s effect on civil war and one on the impact of historical plough use on contemporary female political participation—illustrate the framework and methodology.

A Unified Approach to Measurement Error and Missing Data Details and Extensions

We extend a unified and easy-to-use approach to measurement error and missing data. In our companion article, Blackwell, Honaker, and King give an intuitive overview of the new technique, along with practical suggestions and empirical applications. Here, we offer more precise technical details, more sophisticated measurement error model specifications and estimation procedures, and analyses to assess the approach’s robustness to correlated measurement errors and to errors in categorical variables. These results support using the technique to reduce bias and increase efficiency in a wide variety of empirical research.

Explaining Preferences from Behavior: A Cognitive Dissonance Approach

The standard approach in positive political theory posits that action choices are the consequences of preferences. Social psychology—in particular, cognitive dissonance theory—suggests the opposite: preferences may themselves be affected by action choices. We present a framework that applies this idea to three models of political choice: (1) one in which partisanship emerges naturally in a two-party system despite policy being multidimensional, (2) one in which interactions with people who express different views can lead to empathetic changes in political positions, and (3) one in which ethnic or racial hostility increases after acts of violence. These examples demonstrate how incorporating the insights of social psychology can expand the scope of formalization in political science.

Instrumental Variable Methods for Conditional Effects and Causal Interaction in Voter Mobilization Experiments

ABSTRACT In democratic countries, voting is one of the most important ways for citizens to influence policy and hold their representatives accountable. And yet, in the United States and many other countries, rates of voter turnout are alarmingly low. Every election cycle, mobilization efforts encourage citizens to vote and ensure that elections reflect the true will of the people. To establish the most effective way of encouraging voter turnout, this article seeks to differentiate between (1) the synergy hypothesis that multiple instances of voter contact increase the effectiveness of a single form of contact, and (2) the diminishing returns hypothesis that multiple instances of contact are less effective or even counterproductive. Remarkably, previous studies have been unable to compare these hypotheses because extant approaches to analyzing experiments with noncompliance cannot speak to questions of causal interaction. I resolve this impasse by extending the traditional instrumental variables framework to accommodate multiple treatment–instrument pairs, which allows for the estimation of conditional and interaction effects to adjudicate between synergy and diminishing returns. The analysis of two voter mobilization field experiments provides the first evidence of diminishing returns to follow-up contact and a cautionary tale about experimental design for these quantities. Supplementary materials for this article are available online.