Matthew Gentzkow
Biographic Data
| ID | 1456925 |
|---|---|
| NAME | Matthew Gentzkow |
| GIVEN NAMES | Matthew |
| FAMILY NAME | Gentzkow |
| SIGNATURE | GENTZKOW M |
| AFFILIATIONS | Stanford University |
| ORCID | 0000-0001-7758-8656 |
| VERIFIED | Yes |
| TOTAL WORKS | 27 |
| TOTAL CITATIONS | 987 |
| AUTHOR COUNT | 27 |
| EDITOR COUNT | 0 |
| FIRST PUBLICATION YEAR | 2004 |
| LATEST PUBLICATION YEAR | 2024 |
| H-INDEX | 4 |
The Diffusion and Reach of (Mis)Information on Facebook during the U.S. 2020 Election
Social media creates the possibility for rapid, viral spread of content, but how many posts actually reach millions? And is misinformation special in how it propagates? We answer these questions by analyzing the virality of and exposure to information on Facebook during the U.S. 2020 presidential election. We examine the diffusion trees of the approximately 1 B posts that were re-shared at least once by U.S.-based adults from July 1, 2020, to Feb…
Cross-Country Trends in Affective Polarization
We measure trends in affective polarization in twelve OECD countries over the past four decades. According to our baseline estimates, the United States experienced the largest increase in polarization over this period. Five countries experienced a smaller increase in polarization. Six countries experienced a decrease in polarization. We relate trends in polarization to trends in potential explanatory factors
Like-minded sources on Facebook are prevalent but not polarizing
Many critics raise concerns about the prevalence of ‘echo chambers’ on social media and their potential role in increasing political polarization. However, the lack of available data and the challenges of conducting large-scale field experiments have made it difficult to assess the scope of the problem 1,2 . Here we present data from 2020 for the entire population of active adult Facebook users in the USA showing that content from ‘like-minded’ s…
Asymmetric ideological segregation in exposure to political news on Facebook
Does Facebook enable ideological segregation in political news consumption? We analyzed exposure to news during the US 2020 election using aggregated data for 208 million US Facebook users. We compared the inventory of all political news that users could have seen in their feeds with the information that they saw (after algorithmic curation) and the information with which they engaged. We show that (i) ideological segregation is high and increase…
How do social media feed algorithms affect attitudes and behavior in an election campaign?
We investigated the effects of Facebook’s and Instagram’s feed algorithms during the 2020 US election. We assigned a sample of consenting users to reverse-chronologically-ordered feeds instead of the default algorithms. Moving users out of algorithmic feeds substantially decreased the time they spent on the platforms and their activity. The chronological feed also affected exposure to content: The amount of political and untrustworthy content the…
Affective Polarization Did Not Increase During the Covid-19 Pandemic
We document trends in affective polarization during the COVID-19 pandemic. In our main measure, affective polarization is relatively flat between July 2019 and February 2020, then falls significantly around the onset of the pandemic. Three of five other data sources display a similar downward trend, with two of five data sources showing no significant change. A survey experiment shows that priming respondents to think about the onset of the COVID…
Polarization and public health: Partisan differences in social distancing during the coronavirus pandemic
Cross-Country Trends in Affective Polarization
We measure trends in affective polarization in twelve OECD countries over the past four decades.According to our baseline estimates, the US experienced the largest increase in polarization over this period.Five countries experienced a smaller increase in polarization.Six countries experienced a decrease in polarization.We relate trends in polarization to trends in potential explanatory factors.
Polarization and Public Health: Partisan Differences in Social Distancing during the Coronavirus Pandemic
We study partisan differences in Americans' response to the COVID-19 pandemic.Political leaders and media outlets on the right and left have sent divergent messages about the severity of the crisis, which could impact the extent to which Republicans and Democrats engage in social distancing and other efforts to reduce disease transmission.We develop a simple model of a pandemic response with heterogeneous agents that clarifies the causes and cons…
The Welfare Effects of Social Media
The rise of social media has provoked both optimism about potential societal benefits and concern about harms such as addiction, depression, and political polarization. In a randomized experiment, we find that deactivating Facebook for the four weeks before the 2018 US midterm election (i) reduced online activity, while increasing offline activities such as watching TV alone and socializing with family and friends; (ii) reduced both factual news …
Transparency in Structural Research
We propose a formal definition of transparency in empirical research and apply it to structural estimation in economics. We discuss how some existing practices can be understood as attempts to improve transparency, and we suggest ways to improve current practice, emphasizing approaches that impose a minimal computational burden on the researcher. We illustrate with examples
Measuring Group Differences in High‐Dimensional Choices: Method and Application to Congressional Speech
We study the problem of measuring group differences in choices when the dimensionality of the choice set is large. We show that standard approaches suffer from a severe finite‐sample bias, and we propose an estimator that applies recent advances in machine learning to address this bias. We apply this method to measure trends in the partisanship of congressional speech from 1873 to 2016, defining partisanship to be the ease with which an observer …
Text as Data
An ever-increasing share of human interaction, communication, and culture is recorded as digital text. We provide an introduction to the use of text as an input to economic research. We discuss the features that make text different from other forms of data, offer a practical overview of relevant statistical methods, and survey a variety of applications. (JEL C38, C55, L82, Z13)
Trends in the diffusion of misinformation on social media
In recent years, there has been widespread concern that misinformation on social media is damaging societies and democratic institutions. In response, social media platforms have announced actions to limit the spread of false content. We measure trends in the diffusion of content from 569 fake news websites and 9540 fake news stories on Facebook and Twitter between January 2015 and July 2018. User interactions with false content rose steadily on …
Social Media and Fake News in the 2016 Election
Greater Internet use is not associated with faster growth in political polarization among US demographic groups
Significance By many measures, Americans have become increasingly polarized in recent decades. We study the role of the Internet and social media in explaining this trend. We find that polarization has increased the most among the demographic groups least likely to use the Internet and social media, suggesting that the role of these factors is limited.
Social Media and Fake News in the 2016 Election
Following the 2016 US presidential election, many have expressed concern about the effects of false stories ("fake news"), circulated largely through social media. We discuss the economics of fake news and present new data on its consumption prior to the election. Drawing on web browsing data, archives of fact-checking websites, and results from a new online survey, we find: 1) social media was an important but not dominant source of election new…
Sources of Geographic Variation in Health Care: Evidence From Patient Migration
We study the drivers of geographic variation in U.S. health care utilization, using an empirical strategy that exploits migration of Medicare patients to separate the role of demand and supply factors. Our approach allows us to account for demand differences driven by both observable and unobservable patient characteristics. Within our sample of over-65 Medicare beneficiaries, we find that 40–50% of geographic variation in utilization is attribut…
Bayesian Persuasion
When is it possible for one person to persuade another to change her action? We consider a symmetric information model where a sender chooses a signal to reveal to a receiver, who then takes a noncontractible action that affects the welfare of both players. We derive necessary and sufficient conditions for the existence of a signal that strictly benefits the sender. We characterize sender-optimal signals. We examine comparative statics with respe…
Ideological Segregation Online and Offline
We use individual and aggregate data to ask how the Internet is changing the ideological segregation of the American electorate. Focusing on online news consumption, offline news consumption, and face-to-face social interactions, we define ideological segregation in each domain using standard indices from the literature on racial segregation. We find that ideological segregation of online news consumption is low in absolute terms, higher than the…
The Effect of Newspaper Entry and Exit on Electoral Politics
We use new data on entries and exits of US daily newspapers from 1869 to 2004 to estimate effects on political participation, party vote shares, and electoral competitiveness. Our identification strategy exploits the precise timing of these events and allows for the possibility of confounding trends. We focus our analysis on the years 1869– 1928, and we use the remaining years of data to look at changes over time. We find that newspapers have a r…
Persuasion: Empirical Evidence
We provide a selective survey of empirical evidence on the effects as well as the drivers of persuasive communication. We consider persuasion directed at consumers, voters, donors, and investors. We organize our review around four questions. First, to what extent does persuasion affect the behavior of each of these groups? Second, what models best capture the response to persuasive communication? Third, what are persuaders' incentives, and what l…
What Drives Media Slant? Evidence From U.S. Daily Newspapers
We construct a new index of media slant that measures the similarity of a news outlet's language to that of a congressional Republican or Democrat. We estimate a model of newspaper demand that incorporates slant explicitly, estimate the slant that would be chosen if newspapers independently maximized their own profits, and compare these profit-maximizing points with firms' actual choices. We find that readers have an economically significant pref…
Competition and Truth in the Market for News
In this essay, we evaluate the case for competition in news markets from the perspective of economics. First, we consider the simple proposition that when more points of view are heard and defended, beliefs will converge to the truth. This concept of "competition" is several steps removed from market competition among actual media firms, but it has played a prominent role in the legal arguments for a free press. We then explore three mechanisms b…
Television and Voter Turnout
I use variation across markets in the timing of television's introduction to identify its impact on voter turnout. The estimated effect is significantly negative, accounting for between a quarter and a half of the total decline in turnout since the 1950s. I argue that substitution away from other media with more political coverage provides a plausible mechanism linking television to voting. As evidence for this, I show that the entry of televisio…
Social Media and Fake News in the 2016 Election
Following the 2016 US presidential election, many have expressed concern about the effects of false stories ("fake news"), circulated largely through social media. We discuss the economics of fake news and present new data on its consumption prior to the election. Drawing on web browsing data, archives of fact-checking websites, and results from a new online survey, we find: 1) social media was an important but not dominant source of election new…
Media Bias and Reputation
A Bayesian consumer who is uncertain about the quality of an information source will infer that the source is of higher quality when its reports conform to the consumer's prior expectations. We use this fact to build a model of media bias in which firms slant their reports toward the prior beliefs of their customers in order to build a reputation for quality. Bias emerges in our model even though it can make all market participants worse off. The…
Trends in the diffusion of misinformation on social media
In recent years, there has been widespread concern that misinformation on social media is damaging societies and democratic institutions. In response, social media platforms have announced actions to limit the spread of false content. We measure trends in the diffusion of content from 569 fake news websites and 9540 fake news stories on Facebook and Twitter between January 2015 and July 2018. User interactions with false content rose steadily on …
Competition and Truth in the Market for News
In this essay, we evaluate the case for competition in news markets from the perspective of economics. First, we consider the simple proposition that when more points of view are heard and defended, beliefs will converge to the truth. This concept of "competition" is several steps removed from market competition among actual media firms, but it has played a prominent role in the legal arguments for a free press. We then explore three mechanisms b…
Affective Polarization Did Not Increase During the Covid-19 Pandemic
We document trends in affective polarization during the COVID-19 pandemic. In our main measure, affective polarization is relatively flat between July 2019 and February 2020, then falls significantly around the onset of the pandemic. Three of five other data sources display a similar downward trend, with two of five data sources showing no significant change. A survey experiment shows that priming respondents to think about the onset of the COVID…
Media, Education and Anti-Americanism in the Muslim World
Recent surveys in the United States and the Muslim world show widespread misinformation about the events of September 11, 2001. Using data from 9 predominantly Muslim countries, we study how such beliefs depend on exposure to news media and levels of education. Standard economic theory would predict that increased access to information should cause beliefs to converge. More recent models of biased belief formation suggest that this result might h…
Television and Voter Turnout
I use variation across markets in the timing of television's introduction to identify its impact on voter turnout. The estimated effect is significantly negative, accounting for between a quarter and a half of the total decline in turnout since the 1950s. I argue that substitution away from other media with more political coverage provides a plausible mechanism linking television to voting. As evidence for this, I show that the entry of televisio…
Media Bias and Reputation
A Bayesian consumer who is uncertain about the quality of an information source will infer that the source is of higher quality when its reports conform to the consumer's prior expectations. We use this fact to build a model of media bias in which firms slant their reports toward the prior beliefs of their customers in order to build a reputation for quality. Bias emerges in our model even though it can make all market participants worse off. The…
Competition and Truth in the Market for News
In this essay, we evaluate the case for competition in news markets from the perspective of economics. First, we consider the simple proposition that when more points of view are heard and defended, beliefs will converge to the truth. This concept of "competition" is several steps removed from market competition among actual media firms, but it has played a prominent role in the legal arguments for a free press. We then explore three mechanisms b…
Persuasion: Empirical Evidence
We provide a selective survey of empirical evidence on the effects as well as the drivers of persuasive communication. We consider persuasion directed at consumers, voters, donors, and investors. We organize our review around four questions. First, to what extent does persuasion affect the behavior of each of these groups? Second, what models best capture the response to persuasive communication? Third, what are persuaders' incentives, and what l…
What Drives Media Slant? Evidence From U.S. Daily Newspapers
We construct a new index of media slant that measures the similarity of a news outlet's language to that of a congressional Republican or Democrat. We estimate a model of newspaper demand that incorporates slant explicitly, estimate the slant that would be chosen if newspapers independently maximized their own profits, and compare these profit-maximizing points with firms' actual choices. We find that readers have an economically significant pref…
Bayesian Persuasion
When is it possible for one person to persuade another to change her action? We consider a symmetric information model where a sender chooses a signal to reveal to a receiver, who then takes a noncontractible action that affects the welfare of both players. We derive necessary and sufficient conditions for the existence of a signal that strictly benefits the sender. We characterize sender-optimal signals. We examine comparative statics with respe…
Ideological Segregation Online and Offline
We use individual and aggregate data to ask how the Internet is changing the ideological segregation of the American electorate. Focusing on online news consumption, offline news consumption, and face-to-face social interactions, we define ideological segregation in each domain using standard indices from the literature on racial segregation. We find that ideological segregation of online news consumption is low in absolute terms, higher than the…
The Effect of Newspaper Entry and Exit on Electoral Politics
We use new data on entries and exits of US daily newspapers from 1869 to 2004 to estimate effects on political participation, party vote shares, and electoral competitiveness. Our identification strategy exploits the precise timing of these events and allows for the possibility of confounding trends. We focus our analysis on the years 1869– 1928, and we use the remaining years of data to look at changes over time. We find that newspapers have a r…
Sources of Geographic Variation in Health Care: Evidence From Patient Migration
We study the drivers of geographic variation in U.S. health care utilization, using an empirical strategy that exploits migration of Medicare patients to separate the role of demand and supply factors. Our approach allows us to account for demand differences driven by both observable and unobservable patient characteristics. Within our sample of over-65 Medicare beneficiaries, we find that 40–50% of geographic variation in utilization is attribut…
Social Media and Fake News in the 2016 Election
Greater Internet use is not associated with faster growth in political polarization among US demographic groups
Significance By many measures, Americans have become increasingly polarized in recent decades. We study the role of the Internet and social media in explaining this trend. We find that polarization has increased the most among the demographic groups least likely to use the Internet and social media, suggesting that the role of these factors is limited.
Social Media and Fake News in the 2016 Election
Following the 2016 US presidential election, many have expressed concern about the effects of false stories ("fake news"), circulated largely through social media. We discuss the economics of fake news and present new data on its consumption prior to the election. Drawing on web browsing data, archives of fact-checking websites, and results from a new online survey, we find: 1) social media was an important but not dominant source of election new…
Measuring Group Differences in High‐Dimensional Choices: Method and Application to Congressional Speech
We study the problem of measuring group differences in choices when the dimensionality of the choice set is large. We show that standard approaches suffer from a severe finite‐sample bias, and we propose an estimator that applies recent advances in machine learning to address this bias. We apply this method to measure trends in the partisanship of congressional speech from 1873 to 2016, defining partisanship to be the ease with which an observer …
Text as Data
An ever-increasing share of human interaction, communication, and culture is recorded as digital text. We provide an introduction to the use of text as an input to economic research. We discuss the features that make text different from other forms of data, offer a practical overview of relevant statistical methods, and survey a variety of applications. (JEL C38, C55, L82, Z13)
Trends in the diffusion of misinformation on social media
In recent years, there has been widespread concern that misinformation on social media is damaging societies and democratic institutions. In response, social media platforms have announced actions to limit the spread of false content. We measure trends in the diffusion of content from 569 fake news websites and 9540 fake news stories on Facebook and Twitter between January 2015 and July 2018. User interactions with false content rose steadily on …
Polarization and public health: Partisan differences in social distancing during the coronavirus pandemic
Cross-Country Trends in Affective Polarization
We measure trends in affective polarization in twelve OECD countries over the past four decades.According to our baseline estimates, the US experienced the largest increase in polarization over this period.Five countries experienced a smaller increase in polarization.Six countries experienced a decrease in polarization.We relate trends in polarization to trends in potential explanatory factors.
Polarization and Public Health: Partisan Differences in Social Distancing during the Coronavirus Pandemic
We study partisan differences in Americans' response to the COVID-19 pandemic.Political leaders and media outlets on the right and left have sent divergent messages about the severity of the crisis, which could impact the extent to which Republicans and Democrats engage in social distancing and other efforts to reduce disease transmission.We develop a simple model of a pandemic response with heterogeneous agents that clarifies the causes and cons…
The Welfare Effects of Social Media
The rise of social media has provoked both optimism about potential societal benefits and concern about harms such as addiction, depression, and political polarization. In a randomized experiment, we find that deactivating Facebook for the four weeks before the 2018 US midterm election (i) reduced online activity, while increasing offline activities such as watching TV alone and socializing with family and friends; (ii) reduced both factual news …
Transparency in Structural Research
We propose a formal definition of transparency in empirical research and apply it to structural estimation in economics. We discuss how some existing practices can be understood as attempts to improve transparency, and we suggest ways to improve current practice, emphasizing approaches that impose a minimal computational burden on the researcher. We illustrate with examples
Affective Polarization Did Not Increase During the Covid-19 Pandemic
We document trends in affective polarization during the COVID-19 pandemic. In our main measure, affective polarization is relatively flat between July 2019 and February 2020, then falls significantly around the onset of the pandemic. Three of five other data sources display a similar downward trend, with two of five data sources showing no significant change. A survey experiment shows that priming respondents to think about the onset of the COVID…
Like-minded sources on Facebook are prevalent but not polarizing
Many critics raise concerns about the prevalence of ‘echo chambers’ on social media and their potential role in increasing political polarization. However, the lack of available data and the challenges of conducting large-scale field experiments have made it difficult to assess the scope of the problem 1,2 . Here we present data from 2020 for the entire population of active adult Facebook users in the USA showing that content from ‘like-minded’ s…
Asymmetric ideological segregation in exposure to political news on Facebook
Does Facebook enable ideological segregation in political news consumption? We analyzed exposure to news during the US 2020 election using aggregated data for 208 million US Facebook users. We compared the inventory of all political news that users could have seen in their feeds with the information that they saw (after algorithmic curation) and the information with which they engaged. We show that (i) ideological segregation is high and increase…
How do social media feed algorithms affect attitudes and behavior in an election campaign?
We investigated the effects of Facebook’s and Instagram’s feed algorithms during the 2020 US election. We assigned a sample of consenting users to reverse-chronologically-ordered feeds instead of the default algorithms. Moving users out of algorithmic feeds substantially decreased the time they spent on the platforms and their activity. The chronological feed also affected exposure to content: The amount of political and untrustworthy content the…
Political science (19 works) · Economics (16 works) · Media Influence and Politics (15 works) · Computer Science (14 works) · Business (12 works) · Law (12 works) · Politics (12 works) · Advertising (11 works) · Social Media and Politics (11 works) · Psychology (10 works)