Journal Articles

Roy H. Perlis, Katherine Ognyanova, Mauricio Santillana, Matthew A. Baum, David Lazer, James Druckman, and John Della Volpe. 3/12/2021. “Association of Acute Symptoms of COVID-19 and Symptoms of Depression in Adults.” JAMA Network Open, 4, 3, Pp. e213223-e213223. Publisher's Version
After acute infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a subset of individuals experience persistent symptoms involving mood, sleep, anxiety, and fatigue, which may contribute to markedly elevated rates of major depressive disorder observed in recent epidemiologic studies. In this study, we investigated whether acute coronavirus disease 2019 (COVID-19) symptoms are associated with the probability of subsequent depressive symptoms.
Matthew A. Baum, Dara Kay Cohen, and Susanne Schwarz. 5/6/2020. “(Sex) Crime and Punishment: How Legally Irrelevant Details Influence Crime Reporting and Sanctioning Decisions.” Political Behavior. Publisher's Version
Recent prominent rape cases have raised concerns that the US exhibits a “culture of rape,” wherein victims are often disbelieved and blamed. We present an empirical conceptualization of rape culture, outlining four key features: blaming victims, empathizing with perpetrators, assuming the victims’ consent, and questioning victims’ credibility. In a series of experimental studies, we evaluate the relative impact of different types of rape culture biases on the reporting of rape, and how it is punished. We test how participants’ exposure to legally irrelevant details related to rape culture affects their decision-making. We find that exposure to certain details—relating to the victim’s consent and credibility—significantly decreasesparticipants’ propensities to recommend a rape case be reported to police or to advocate for a severe punishment for the perpetrator. The same biases do not emerge in robbery cases, suggesting that rape is regarded differently from other violent crimes.
Justin de Benedictis-Kessner, Matthew A. Baum, J. Berinsky, Adam, and Teppei Yamamoto. 11/2019. “Persuading the Enemy: Estimating the Persuasive Effects of Partisan Media with the Preference-Incorporating Choice and Assignment Design.” American Political Science Review, 113, 4, Pp. 902-916. Publisher's Version
Does media choice cause polarization, or merely reflect it? We investigate a critical aspect of this puzzle: how partisan media contribute to attitude polarization among different groups of media consumers. We implement a new experimental design, called the Preference-Incorporating Choice and Assignment (PICA) design, that incorporates both free choice and forced exposure. We estimate jointly the degree of polarization caused by selective exposure and the persuasive effect of partisan media. Our design also enables us to conduct sensitivity analyses accounting for discrepancies between stated preferences and actual choice, a potential source of bias ignored in previous studies using similar designs. We find that partisan media can polarize both its regular consumers and inadvertent audiences who would otherwise not consume it, but ideologically-opposing media potentially also can ameliorate existing polarization between consumers. Taken together, these results deepen our understanding of when and how media polarize individuals. 
Matthew A. Baum, Dannagal G. Young, and Duncan Prettyman. 5/13/2019. “vMOBilize: Gamifying Civic Learning and Political Engagement in a Classroom Context.” Journal of Political Science Education. Publisher's Version

This study presents the results of a quasi-experiment (N= 307) conducted over the course of 10 weeks in Spring of 2016 to assess the effectiveness of a game platform designed to facilitate political engagement, attention, efficacy, knowledge, and participation among college students. Results indicate positive effects of gameplay on several key dimensions of political engagement, including voter registration, virtual political participation (following a candidate on Twitter, liking a candidate on Facebook, and watching debates), and consumption of public affairs information (including National Public Radio, non-NPR political talk radio, and online news aggregator sites). Additionally, gameplay provided significantly greater benefits to students with the lowest rates of political knowledge at baseline. Overall, participants reported high rates of game satisfaction, with 79% of participants reporting being very to somewhat pleased if they were asked to play the game again. These results are discussed in terms of the implications for civics education, pedagogy, and political engagement among young people.

Dean Knox, Teppei Yamamoto, Matthew A. Baum, and Adam Berinsky. 4/30/2019. “Design, Identification, and Sensitivity Analysis for Patient Preference Trials.” Journal of the American Statistical Association, 114, 528, Pp. 1532-1546. Publisher's Version

Social and medical scientists are often concerned that the external validity of experimental results may be compromised because of heterogeneous treatment effects. If a treatment has different effects on those who would choose to take it and those who would not, the average treatment effect estimated in a standard randomized controlled trial (RCT) may give a misleading picture of its impact outside of the study sample. Patient preference trials (PPTs), where participants’ preferences over treatment options are incorporated in the study design, provide a possible solution. In this paper, we provide a systematic analysis of PPTs based on the potential outcomes framework of causal inference. We propose a general design for PPTs with multi-valued treatments, where participants state their pre- ferred treatments and are then randomized into either a standard RCT or a self-selection condition. We derive nonparametric sharp bounds on the average causal effects among each choice-based sub- population of participants under the proposed design. We also propose a sensitivity analysis for the violation of the key ignorability assumption sufficient for identifying the target causal quantity. The proposed design and methodology are illustrated with an original study of partisan news media and its behavioral impact.

Matthew A. Baum and Yuri M. Zhukov. 4/9/2019. “Media Ownership and News Coverage of International Conflict.” Political Communication, 36, 1, Pp. 36-63. Publisher's Version
How do differences in ownership of media enterprises shape news coverage of international conflict? We examine this relationship using a new dataset of 591,532 articles on US-led multinational military operations in Libya, Iraq, Afghanistan and Kosovo, published by 2,505 newspapers in 116 countries. We find that ownership chains exert a homogenizing effect on the content of newspapers’ coverage of foreign policy, resulting in coverage across co-owned papers that is more similar in scope (what they cover), focus (how much “hard” relative to “soft” news they offer), and diversity (the breadth of topics they include in their coverage of a given issue) relative to coverage across papers that are not co-owned. However, we also find that competitive market pressures can mitigate these homogenizing effects, and incentivize co-owned outlets to differentiate their coverage. Restrictions on press freedom have the opposite impact, increasing the similarity of coverage within ownership chains.
Matthew A. Baum and Philip B. K. Potter. 4/2019. “Media, Public Opinion, and Foreign Policy in the Age of Trump.” Journal of Politics, 81, 2, Pp. 747-756. Publisher's Version

Democratic publics have always struggled to constrain their elected leaders’ foreign policy actions. By its nature, foreign policy creates information asymmetries that disadvantage citizens in favor of leaders. But has this disadvantage deepened with the advent of the Internet and the resulting fundamental changes in the media and politics? We argue that it has. The current information and political environments erode constraint by inclining constituents to reflexively and durably back “their” leaders and disapprove of opposition. These changes make it harder for citizens to informationally “catch up” with and constrain leaders because views that contradict citizens’ beliefs are less likely to break through when media are fragmented and siloed. These changes have important implications for theories concerning the democratic peace, audience costs, rally effects, and diversionary war. They may also contribute to instability in foreign policy by contributing to sudden and destabilizing changes in public opinion that undercut commitments abroad.

Kenneth Joseph, Briony Swire-Thompson, Hannah Masuga, Matthew A. Baum, and David Lazer. 2019. “Polarized, Together: Comparing Partisan Support for Trump’s Tweets Using Survey and Platform-based Measures.” Thirteenth international AAAI conference on web and social media (ICWSM) 13 (1), Pp. 290-301. Munich, Germany: Association for the Advancement of Artificial Intelligence. Publisher's Version

Using both survey- and platform-based measures of support, we study how polarization manifests for 4,313 of President Donald Trump’s tweets since he was inaugurated in 2017. We find high levels of polarization in response to Trump’s tweets. However, after controlling for mean differences, we surprisingly find a high degree of agreement across partisan lines across both survey and platform-based measures. This suggests that Republicans and Democrats, while disagreeing on an absolute level, tend to agree on the relative quality of Trump’s tweets. We assess potential reasons for this, for example, by studying how support changes in response to tweets containing positive versus negative language.We also explore how Democrats and Republicans respond to tweets containing insults of individuals with particular socio-demographics, finding that Republican support decreases when Republicans, relative to Democrats, are insulted, and Democrats respond negatively to insults of women and members of the media.

David M. J. Lazer, Matthew A. Baum, Yochai Benkler, Adam J. Berinsky, Kelly M. Greenhill, Filippo Menczer, Miriam J. Metzger, Brendan Nyhan, Gordon Pennycook, David Rothschild, Michael Schudson, Steven A. Sloman, Cass R. Sunstein, Emily A. Thorson, Duncan J. Watts, and Jonathan L. Zittrain. 3/2018. “The science of fake news.” Science, 359, 6380, Pp. 1094-1096. Publisher's Version
The rise of fake news highlights the erosion of long-standing institutional bulwarks against misinformation in the internet age. Concern over the problem is global. However, much remains unknown regarding the vulnerabilities of individuals, institutions, and society to manipulations by malicious actors. A new system of safeguards is needed. Below, we discuss extant social and computer science research regarding belief in fake news and the mechanisms by which it spreads. Fake news has a long history, but we focus on unanswered scientific questions raised by the proliferation of its most recent, politically oriented incarnation. Beyond selected references in the text, suggested further reading can be found in the supplementary materials.
science_of_fake_news.pdf science_supplemental_materials.pdf
Matthew Baum, Dara Kay Cohen, and Yuri M. Zhukov. 2018. “Does Rape Culture Predict Rape? Evidence from U.S. Newspapers, 2000-2013.” Quarterly Journal of Political Science, 13, 3, Pp. 263-289. Publisher's Version
We offer the first quantitative analysis of rape culture in the United States. Observers have long worried that biased news coverage of rape - which blames victims, empathizes with perpetrators, implies consent, and questions victims’ credibility - may deter victims from  coming forward, and ultimately increase the incidence of rape. We present a theory of how rape culture might shape the preferences and choices of perpetrators, victims and law enforcement, and test this theory with data on news stories about rape published in U.S. newspapers between 2000 and 2013. We find that rape culture in the media predicts both the  frequency of rape and its pursuit through the local criminal justice system. In jurisdictions where rape culture was more prevalent, there were more documented rape cases, but authorities were less vigilant in pursuing them. 
rapecultureqjps.doc rapecultureqjps_appendix.pdf
Matthew A Baum and Yuri M. Zhukov. 2015. “Filtering revolution: Reporting bias in international newspaper coverage of the Libyan civil war.” Journal of Peace Research . Publisher's Version
Reporting bias – the media’s tendency to systematically underreport or overreport certain types of events – is a persistent problem for participants and observers of armed conflict. We argue that the nature of reporting bias depends on how news organizations navigate the political context in which they are based. Where government pressure on the media is limited – in democratic regimes – the scope of reporting should reflect conventional media preferences toward novel, large-scale, dramatic developments that challenge the conventional wisdom and highlight the unsustainability of the status quo. Where political constraints on reporting are more onerous – in non-democratic regimes – the more conservative preferences of the state will drive the scope of coverage, emphasizing the legitimacy and inevitability of the prevailing order. We test these propositions using new data on protest and political violence during the 2011 Libyan uprising and daily newspaper coverage of the Arab Spring from 113 countries. We uncover evidence of a status-quo media bias in non-democratic states, and a revisionist bias in democratic states. Media coverage in non-democracies underreported protests and nonviolent collective action by regime opponents, largely ignored government atrocities, and overreported those caused by rebels. We find the opposite patterns in democratic states.
Matthew A. Baum and Philip B. K. Potter. 2013. “Looking for Audience Costs in all the Wrong Places: Electoral Institutions, Media Access, and Democratic Constraint.” The Journal of Politics . Publisher's Version
For leaders to generate credibility through audience costs, there must be mechanisms in place that enable citizens to learn about foreign policy failures. However, scholars have paid relatively little attention to variations among democracies in the extent to which the public is able to obtain this sort of information. We argue here that electoral institutions play this role by influencing the number of major political parties in a country and, with it, the extent and depth of opposition to the executive. Opposition leads to whistle-blowing, which makes it more likely that that the public will actually hear about a leader’s foreign policy blunders. The effectiveness of this whistle-blowing, however, is conditional on the public’s access to the primary conduit for communication between leaders and citizens: the mass media. We test these expectations statistically, demonstrating that leaders in systems with these attributes fare better with respect to their threats and the reciprocation of conflicts that they initiate. These findings suggest that democracies are not automatically able to generate credibility through audience costs and that the domestic institutions and political processes that link the public and leaders must be taken seriously.
potterbaumjopsupplementalappendix.pdf potterbaumjop.pdf
Kathleen Hancock, Marijke Breuning, and Matthew A. Baum. 2013. “Women and Pre-Tenure Scholarly Productivity in International Studies: An Investigation into the Leaky Career Pipeline.” International Studies Perspective . Publisher's Version
Matthew A. Baum. 2012. “The Iraq Coalition of the Willing and (Politically) Able: Party Systems, the Press, and Public Influence on Foreign Policy.” American Journal of Political Science . Publisher's Version
Media outlets in multiparty electoral systems tend to report on a wider range of policy issues than media in two-party systems. They thus make more competing policy frames available to citizens. This suggests that a “free press” is insufficient to hold governments accountable. Rather, we should observe more challenges to the governments’ preferred frames and more politically aware citizens in multiparty democracies. Such citizens should thus be better equipped to hold their leaders accountable, relative to their counterparts in two-party democracies. I propose a mechanism through which democratic publics can sometimes constrain their leaders in foreign policy. I test hypotheses derived from my theory with cross-national data on the content of news coverage of Iraq, on public support for the war, and on decisions to contribute troops to the Iraq “Coalition of the Willing.” I find that citizens in countries with larger numbers of parties confronted more critical and diverse coverage of Iraq, while those with more widespread access to mass media were more likely to oppose the war and their nations likely to contribute fewer troops to the Coalition.
Matthew A. Baum. 2011. “Red State, Blue State, Flu State: Media Self-Selection and Partisan Gaps in Swine Flu Vaccinations.” Journal of Health Politics, Policy and Law. Publisher's Version
Prevailing theories hold that U.S. public support for a war depends primarily on its degree of success, U.S. casualties, or conflict goals. Yet, research into the framing of foreign policy shows that public perceptions concerning each of these factors are often endogenous and malleable by elites. In this article, we argue that both elite rhetoric and the situation on the ground in the conflict affect public opinion, but the qualities that make such information persuasive vary over time and with circumstances. Early in a conflict, elites (especially the president) have an informational advantage that renders public perceptions of “reality” very elastic. As events unfold and as the public gathers more information, this elasticity recedes, allowing alternative frames to challenge the administration’s preferred frame. We predict that over time the marginal impact of elite rhetoric and reality will decrease, although a sustained change in events may eventually restore their influence. We test our argument through a content analysis of news coverage of the Iraq war from 2003 through 2007, an original survey of public attitudes regarding Iraq, and partially disaggregated data from over 200 surveys of public opinion on the war.
Philip K. Potter and Matthew A. Baum. 2010. “Democratic Peace, Domestic Audience Costs, and Political Communication.” Political Communication . Publisher's Version

This article addresses a gap in the literature connecting the empirical observation of a democratic peace to a theoretical mechanism based on domestic audience costs. We argue that the link between these literatures lies in the way leaders reach he ultimate source of audience costs – the public. The audience cost argument implicitly requires a free press because, without it, the public has no way of reliably assessing the success or failure of a leader’s foreign policy. Hence leaders can credibly commit through audience costs only when the media is an effective and independent actor. The implication is that while leaders might gain at home by controlling the media, they do so at the cost of their capacity to persuade foreign leaders that their “hands are tied.”

Matthew A. Baum and Tim Groeling. 2010. “Reality Asserts Itself: Public Opinion on Iraq and the Elasticity of Reality.” International Organization . Publisher's Version
Prevailing theories hold that U.S. public support for a war depends primarily on its degree of success, U.S. casualties, or conflict goals. Yet, research into the framing of foreign policy shows that public perceptions concerning each of these factors are often endogenous and malleable by elites. In this article, we argue that both elite rhetoric and the situation on the ground in the conflict affect public opinion, but the qualities that make such information persuasive vary over time and with circumstances. Early in a conflict, elites (especially the president) have an informational advantage that renders public perceptions of “reality” very elastic. As events unfold and as the public gathers more information, this elasticity recedes, allowing alternative frames to challenge the administration’s preferred frame. We predict that over time the marginal impact of elite rhetoric and reality will decrease, although a sustained change in events may eventually restore their influence. We test our argument through a content analysis of news coverage of the Iraq war from 2003 through 2007, an original survey of public attitudes regarding Iraq, and partially disaggregated data from over 200 surveys of public opinion on the war.
Matthew A. Baum and Tim Groeling. 2009. “Journalists’ Incentives and Media Coverage of Elite Foreign Policy Evaluations.” Conflict Management and Peace Science. Publisher's Version

Scholars have long recognized that public support for presidential uses of military force depends critically on elite support. Similarly, scholars have argued that the media “index” their coverage of foreign policy to reflect the responses of partisan (particularly congressional) elites. We argue that journalists' choices also play an important role by systematically (and predictably) skewing the elite rhetoric presented to the public. In particular, we argue that criticism of the president by his own party is disproportionately likely to be broadcast -- particularly in unified government -- and that such criticism should be exceptionally persuasive to citizens. To separate the media’s independent effect from that of the actual tenor of elite discourse, as presented in the news, we investigate all interviews with members of Congress on network television Sunday morning political interview shows between 1980 and 2003. We then determined which comments were selected for inclusion on the evening news and compare the characteristics of such comments to those that were not selected, both during periods immediately following major U.S. uses of military force and during “normal” periods. We find that the evening news presents a biased sample of elite rhetoric, heavily over-representing criticism of the president by his own party, while under-representing supportive rhetoric. Our findings indicate that future studies of public opinion and U.S. foreign policy must take into account the intervening role of journalists, who function as strategic, self-interested gatekeepers of public information regarding foreign policy events.



You can download a pdf version of the paper, here.

Matthew A. Baum and Tim Groeling. 2009. “New Media and the Polarization of American Political Discourse.” Political Communication . Publisher's Version

Scholars of political communication have long examined newsworthiness by focusing on the “gatekeepers,” or organizations involved in newsgathering (Lewin 1947, White 1950, Sigal 1973, Gans 1979). However, in recent years these gatekeeper organizations have increasingly been joined or even supplanted by “new media” competitors, including cable news, talk radio, and even amateur bloggers. The standards by which this new class of gatekeepers evaluates news are at best partially explained by prior studies focused on “professional” journalists. In this study, we seek to correct this oversight. We do so by content analyzing five online news sources – including wire service, cable news, and blog sites – in order to compare their gatekeeping decisions in the four months prior, and approximately three weeks immediately following, the 2006 midterm election. To determine each day’s major political news, we collected all stories from Reuters’ and AP’s “Top Political News” sections. We then investigated whether a given story was also chosen to appear on each wire’s Top News page (indicating greater perceived newsworthiness than those that were not chosen) and compare the wires’ editorial choices to those of more partisan blogs (from the left:, and from the right: and cable outlets ( We find evidence of greater partisan filtering on the latter three web sources, and relatively greater reliance on traditional newsworthiness criteria on the news wires.


You can download this article, in pdf format, here.

Matthew A. Baum and Tim Groeling. 2008. “Crossing the Water’s Edge: Elite Rhetoric, Media Coverage, and the Rally-Round-the-Flag Phenomenon.” Journal of Politics . Publisher's Version

The most widely accepted explanation for the rally-round-the-flag phenomenon is a relative absence of elite criticism in the news during the initial stages of foreign crises.  In this study we argue that the nature and extent of elite debate may matter less than media coverage of any such debate, and that these often systematically diverge.  We also argue that not all messages in this debate matter equally for public opinion. Rather, the persuasiveness of elite messages depends on their credibility, which, in turn, arises out of an interaction between the sender, receiver, and message. Hence, only by understanding the interactions between elites, the public, and the press can we account for variations in public responses to presidential foreign policy initiatives. We test our theory by examining public opinion data and network news coverage of all major U.S. uses of military force from 1979 to 2003. We content analyze all congressional evaluations of the president and the executive branch of government from the three network evening newscasts within 60-day time periods centered on the start date of each use of force. Our results offer strong support for the theory.



You can download this paper, in pdf format, here.