Working Papers and Papers Under Review

Park, Sunhee, and David J. Hendry. "Reassessing Schoenfeld Residual Tests of Proportional Hazards in Political Science Event History Analyses." (Revised and resubmitted to American Journal of Political Science).
Abstract: An underlying assumption of proportional hazards models is that the effect of a change in a covariate on the hazard rate of event occurrence is constant over time. For scholars using the Cox model, a Schoenfeld residual-based test has become the disciplinary standard for detecting violations of this assumption. However, using this test requires researchers to make a choice about a transformation of the time scale. In practice, this choice has largely consisted of arbitrary decisions made without justification. Using replications and simulations, we demonstrate that the decision about time transformations can have profound implications for the conclusions reached. In particular, we show that researchers can make far more informed decisions by paying closer attention to the presence of outlier survival times and levels of censoring in their data. We suggest a new standard for best practices in Cox diagnostics that buttresses the current standard with in-depth exploratory data analysis.
[Main - pdf] [Appendix - pdf]

Hendry, David J. "Small-group Conformity and Political Attitudes." (Under review).
Abstract: Public responses to attitudinal questions tapping sensitive social issues are likely to paint an optimistic picture of the degree to which individuals adhere to desirable social norms. But little is known empirically about how social pressures operate at the level of interpersonal interactions. This study conducts a laboratory experiment to address the question of how even minimal social pressure leads to conformity with respect to attitude expressions about adherence to egalitarian norms. Baseline attitudinal measurements were taken of subjects, and then those measurements were used to exert social pressure in a contrived group setting. An asymmetric effect was found in which subjects who were willing to espouse an inegalitarian attitude in private were more likely to succumb to social pressure to change their expressed attitudes when faced with an opposed group opinion. For subjects who espouse egalitarian attitudes in private, social pressure to provide an inegalitarian response has little impact.
[Main - pdf] [Appendix - pdf]

Gerber, Alan S., Gregory A. Huber, Daniel R. Biggers, and David J. Hendry. "Can Political Participation Prevent Crime? Results from a Field Experiment about Citizenship, Participation, and Criminality." (Under review).
Abstract: Democratic theory and prior empirical work support the view that political participation, by promoting social integration and pro-social attitudes, can reduce an individual's propensity for anti-social behavior, such as committing a crime. Previous empirical investigations have been limited to observational research, which is vulnerable to bias if there are omitted factors that affect both the propensity to participate and the risk of criminality. We present results from a field experiment in which 552,525 subjects aged 18-20 were encouraged to register and vote. Consistent with previous observational findings, we first confirm that there is a negative association between participation and subsequent criminality. However, comparing the randomly formed treatment and control groups, we find that although the intervention increased participation, it did not produce any reduction in subsequent criminality. Our results thus suggest that while participation is correlated with criminality, encouraging registration and voting has no causal effect on subsequent criminal behavior.
[Main - pdf] [Appendix - pdf]


Publications

Gerber, Alan S., Gregory A. Huber, Marc Meredith, Daniel R. Biggers, and David J. Hendry. "Can Incarcerated Felons Be (Re)integrated into the Political System? Results from a Field Experiment." (Conditionally Accepted at American Journal of Political Science).
Abstract: How does America's high rate of incarceration shape political participation? Few studies have examined the direct effects of incarceration on patterns of political engagement. Answering this question is particularly relevant for the 93% of formerly incarcerated individuals who are eligible to vote. Drawing on new administrative data from Connecticut, we present evidence from a field experiment showing that a simple informational outreach campaign to released felons can recover a large proportion of the reduction in participation observed following incarceration. The treatment effect estimates imply that efforts to reintegrate released felons into the political process can substantially reduce the participatory consequences of incarceration.
[Main - pdf] [Appendix - pdf]

Gerber, Alan S., Kevin Arceneaux, Cheryl Boudreau, Conor M. Dowling, D. Sunshine Hillygus, Thomas R. Palfrey, Daniel R. Biggers, and David J. Hendry. Forthcoming. "Reporting Guidelines for Experimental Research: A Report from the Experimental Research Section Standards Committee." Journal of Experimental Political Science.
Abstract: The Standards Committee of the Experimental Research section of the American Political Science Association has produced reporting guidelines that aim to increase the clarity of experimental research reports. This paper describes the Committee's rationale for the guidelines it developed and includes our Recommended Reporting Standards for Experiments (Laboratory, Field, Survey). It begins with a content analysis of current reporting practices in published experimental research. Although researchers report most important aspects of their experimental designs and data, we find substantial omissions that could undermine the clarity of research practices and the ability of researchers to assess the validity of study conclusions. With the need for reporting guidelines established, the report describes the process the Committee used to develop the guidelines, the feedback received during the comment period, and the rationale for the final version of the guidelines.
[Local pdf] [Online Appendix]

Gerber, Alan S., Gregory A. Huber, Daniel R. Biggers, and David J. Hendry. 2014. "Ballot Secrecy Concerns and Voter Mobilization: New Experimental Evidence about Message Source, Context, and the Duration of Mobilization Effects." American Politics Research 42(5): 896– 923.
Abstract: Recent research finds that doubts about the integrity of the secret ballot as an institution persist among the American public. We build on this finding by providing novel field experimental evidence about how information about ballot secrecy protections can increase turnout among registered voters who had not previously voted. First, we show that a private group's mailing designed to address secrecy concerns modestly increased turnout in the highly contested 2012 Wisconsin gubernatorial recall election. Second, we exploit this and an earlier field experiment conducted in Connecticut during the 2010 congressional midterm election season to identify the persistent effects of such messages from both governmental and non-governmental sources. Together, these results provide new evidence about how message source and campaign context affect efforts to mobilize previous non-voters by addressing secrecy concerns, as well as show that attempting to address these beliefs increases long term participation.
[DOI] [Local pdf] [Online Appendix] [Replication Materials]

Althaus, Scott L., Nathaniel Swigger, Svitlana Chernykh, David J. Hendry, Sergio C. Wals, and Christopher Tiwald. 2014. "Uplifting Manhood to Wonderful Heights? News Coverage of the Human Costs of Military Conflict from World War One to Gulf War Two." Political Communication 31(2): 193–217.
Abstract: Domestic political support is an important factor constraining the use of American military power around the world. Although the dynamics of war support are thought to reflect a cost-benefit calculus, with costs represented by numbers of friendly war deaths, no previous study has examined how information about friendly, enemy, and civilian casualties is routinely presented to domestic audiences. This paper establishes a baseline measure of historical casualty reporting by examining New York Times coverage of five major wars that occurred over the past century. Despite important between-war differences in the scale of casualties, the use of conscription, the type of warfare, and the use of censorship, the frequency of casualty reporting and the framing of casualty reports has remained fairly consistent over the past 100 years. Casualties are rarely mentioned in American war coverage. When casualties are reported, it is often in ways that minimize or downplay the human costs of war.
[DOI] [Local pdf] [Online Appendix] [Contact corresponding author]

Hendry, David J. 2014. "Data Generation for the Cox Proportional Hazards Model with Time-Dependent Covariates: A Method for Medical Researchers." Statistics in Medicine 33(3): 436–454.
Abstract: The proliferation of longitudinal studies has increased the importance of statistical methods for time-to-event data that can incorporate time-dependent covariates. The Cox proportional hazards model is one such method that is widely used. As more extensions of the Cox model with time-dependent covariates are developed, simulations studies will grow in importance as well. An essential starting point for simulation studies of time-to-event models is the ability to produce simulated survival times from a known data generating process. This paper develops a method for the generation of survival times that follow a Cox proportional hazards model with time-dependent covariates. The method presented relies on a simple transformation of random variables generated according to a truncated piecewise exponential distribution, and allows practitioners great flexibility and control over both the number of time-dependent covariates and the number of time periods in the duration of follow-up measurement. Within this framework, an additional argument is suggested that allows researchers to generate time-to-event data in which covariates change at integer-valued steps of the time scale. The purpose of this approach is to produce data for simulation experiments that mimic the types of data structures applied researchers encounter when using longitudinal biomedical data. Validity is assessed in a set of simulation experiments and results indicate that the proposed procedure performs well in producing data that conform to the assumptions of the Cox proportional hazards model.
[DOI] [Local pdf]

Althaus, Scott L., Nathaniel Swigger, Svitlana Chernykh, David J. Hendry, Sergio C. Wals, and Christopher Tiwald. 2011. "Assumed Transmission in Political Science: A Call for Bringing Description Back In." Journal of Politics 73(4): 1065–1080.
Abstract: News outlets cannot serve as reliable conveyors of social facts, nor do their audiences crave such content. Nonetheless, much political science scholarship assumes that objective information about social, political, and economic topics is routinely transmitted to the mass public through the news. This article addresses the problem of selection bias in news content and illustrates the problem with a content analytic study of New York Times coverage given to American war deaths in five major conflicts that occurred over the past century. We find that news coverage of war deaths is unrelated to how many American combatants have recently died. News coverage is more likely to mention war deaths when reporting combat operations and less likely to mention them when a war is going well. These findings underscore the need to document selection biases in information flows before theorizing about proximate causes underlying the relationships between political systems and public opinion.
[DOI] [Online Appendix] [Replication Data]

Hendry, David J., Robert A. Jackson, and Jeffery J. Mondak. 2009. "Abramoff, Email, and the Mistreated Mistress: Scandal and Character 2006 Elections." In Fault Lines: Why the Republicans Lost Congress, eds., Jeffery J. Mondak and Dona-Gene Mitchell. New York: Routledge pp. 84–110.
[Publisher] [Google]