Research

2020
Irene Pasquetto, Matthew A. Baum, Eaman Jahani, and Alla Baranovsky. 5/27/2020. Understanding Misinformation on Mobile Instant Messengers (MIMs) in Developing Countries. Shorenstein Center. Cambridge: Harvard Kennedy School, Shorenstein Center of Media, Politics and Public Policy. Publisher's Version misinfo-on-mims-shorenstein-center-may-2020.pdf
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.
sexcrimeandpunishment_polbehavior.pdf
Matthew A. Baum, Katherine Ognyanova, and David Lazer. 4/29/2020. “These Three Governors are Reopening Their States Faster than Their Voters Want: That's What Our Polling Found in Florida, Georgia, and Tennessee.” The Washington Post Monkey Cage. Publisher's Version
Matthew A. Baum. 3/30/2020. “Trump's Coronavirus Approval Rating: Why its Going Up.” Los Angeles Times. Publisher's Version
See also: Op-Eds, Politics
2019
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. 
mediachoice_apsr_preprint.pdf
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.

vmobilize_jpe_preprint.pdf
Justin de Benedictis-Kessner, Matthew A. Baum, and Adam J. Berinsky. 5/9/2019. “Polarization and Media Usage: Disentangling Causality.” In Oxford Handbook of Electoral Persuasion. New York: Oxford University Press. Publisher's Version
This chapter examines the literature concerning media choice and partisan polarization.  The past few decades have seen enormous growth in the number of television and internet news sources, giving consumers dramatically increased choices.  Previous research has suggested two distinct links between media choice and partisan polarization: partisan media as a reflectionof polarization, as partisans self-select into media that conforms with their preexisting views, or as a causeof polarization, when outlets present one-sided stories that persuade people to adopt more extreme views.  This chapter discusses how the literature in these two research traditions has diverged, as well as more recent research attempting to bridge this divide.  Using novel methods, these studies have drawn together both self-selection and causal research designs to provide a more complete picture of media choice effects, and expanded the literature to more recent mediums, including the internet and social media.
polarizationcausality180806.pdf
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.

mediachoicemethod_final.pdf
Matthew Barreto, Chris Warshaw, Matthew A. Baum, Bryce J. Dietrich, Rebecca Goldstein, and Maya Sen. 4/22/2019. “New Research Shows Just How Badly a Citizenship Question Would Hurt the 2020 Census.” Washington Post Monkey Cage. Publisher's Version
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.
bz_ownership_final.pdf
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.

baum_potter_jop_preprint.pdf
Matthew A. Baum and Dannagal G. Young. 2019. “The “Daily Them": Hybridity, Political Polarization and Presidential Leadership in a Digital Media Age.” In New Directions in Public Opinion Research, Third Edition. Routledge. Publisher's Version baumyoung_dailythem_proofs.pdf
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.

polarizedtogether_icwsm.pdf
2018
Matthew A. Baum, Dara Kay Cohen, Susanne Schwarz, and Yuri Zhukov. 9/27/2018. “The way Kavanaugh’s supporters are talking about sexual assault allegations can be dangerous, our new study finds.” The Monkey Cage (Washingtonpost.com). Publisher's Version the_way_kavanaughs_supporters_are_talking_about_sexual_assault_allegations_can_be_dangerous_our_ne.pdf
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. 2018. “Reporting Bias and Information Warfare”. Publisher's Version
International Studies Association Annual Convention
2017
Matthew A. Baum and David Lazer. 5/8/2017. “Google and Facebook aren't fighting fake news with the right weapons.” Los Angeles Times. URL
See also: Op-Eds
Matthew Baum, David Lazer, Nir Grinberg, Lisa Friedland, Kenneth Joseph, Will Hobbs, and Carolina Mattsson. 5/2017. “Combating Fake News: An Agenda for Research and Action.” In . Cambridge, MA: Shorenstein Center. Publisher's Version

Drawn from presentations by
Yochai Benkler (Harvard), Adam Berinsky (MIT), Helen Boaden (BBC), Katherine Brown (Council on Foreign Relations), Kelly Greenhill (Tufts and Harvard), David Lazer (Northeastern), Filippo Menczer (Indiana), Miriam Metzger (UC Santa Barbara), Brendan Nyhan (Dartmouth), Eli Pariser (UpWorthy), Gordon Pennycook (Yale), Lori Robertson (FactCheck.org), David Rothschild (Microsoft Research), Michael Schudson (Columbia), Adam Sharp (formerly Twitter), Steven Sloman (Brown), Cass Sunstein (Harvard), Emily Thorson (Boston College), and Duncan Watts (Microsoft Research).

Executive Summary

Recent shifts in the media ecosystem raise new concerns about the vulnerability of democratic societies to fake news and the public’s limited ability to contain it. Fake news as a form of misinformation benefits from the fast pace that information travels in today’s media ecosystem, in particular across social media platforms. An abundance of information sources online leads individuals to rely heavily on heuristics and social cues in order to determine the credibility of information and to shape their beliefs, which are in turn extremely difficult to correct or change. The relatively small, but constantly changing, number of sources that produce misinformation on social media offers both a challenge for real-time detection algorithms and a promise for more targeted socio-technical interventions.

Matthew A. Baum. 2017. Report on Network Sunday Morning Talk Show Content and Ratings, Comparing 1983, 1999, and 2015. Publisher's Version
We studied the content and Nielsen ratings for interviews on the three network Sunday morning talk shows—Meet the Press (henceforth MTP), Face the Nation (FTN), and This Week (TW). We compared three time periods—1983 (MTP, FTN), 1999 (all three shows), and 2015 (all three shows). In order to insure apples-to-apples comparisons, for over time comparisons, we either restricted our analyses to MTP and FTN or analyzed the data with and without TW. For “overall” snapshots we included all three shows (MTP, FTN, TW). Our goals were fourfold: (1) identify any discernable trends in the topics and types of guests featured on the Sunday talk shows, (2) identify any trends in audience ratings, (3) assess whether and to what extent trends in topics and guests correlate with audience ratings, and (4) assess whether, to what extent, and under what circumstances, the Sunday talk shows influence the subsequent news agenda.

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