Congrats to Matt Gentzkow on winning the JBC Medal!

Huge congratulations to Matt Gentzkow for winning the John Bates Clark medal! Here is the AEA’s write up of his work.

Matthew Gentzkow has made fundamental contributions to our understanding of the economic forces driving the creation of media products, the changing nature and role of media in the digital environment, and the effect of media on education and civic engagement. He has thus emerged as a leader in a new generation of microeconomists applying economic methods to analyze questions that were historically analyzed by non-economists. His empirical work combines novel data, innovative identification strategies and careful empirical methods to answer questions at the interface of economics, political science, and sociology.  This work is complemented by significant theoretical work on information, communication, and persuasion.  Gentzkow, both on his own and in collaboration with his frequent co-author, Jesse Shapiro, has played a primary role in establishing a new and extremely promising empirical literature on the economics of the news media.

A first set of Gentzkow’s papers studies political bias in the news media.  In “What Drives Media Slant? Evidence from U.S. Daily Newspapers” (Econometrica, 2010), Gentzkow and co-author Jesse Shapiro use textual analysis of a large set of newspaper articles to classify content as more Republican or more Democrat (“media slant”).  This is done using statistical analysis of phrases that differentially show up in Republican versus Democrat Senators’ speeches in the Senate. These constructed measures of media slant match well with conventional wisdom and with other, more ad-hoc and subjective newspaper political classification. Gentzkow and Shapiro then use these measures to estimate demand for newspapers, and to model the newspaper owner’s choice of media slant. They find that most of a newspaper’s media slant can be explained by the preferences of its readers rather than by the tastes of its owner.  The second part of the paper tries to sort out whether the bias of individual papers is driven by “demand” – i.e. the political biases of their target audience – or “supply”, i.e. the idiosyncratic preferences of the owners. They find that it is mostly demand.

In “Ideological Segregation Online and Offline” (Quarterly Journal of Economics, 2011), Gentzkow and Shapiro look for evidence of the so-called internet “echo chamber”, where people of similar ideological bent talk solely to one another when they are online. Their paper uses internet browsing data to show that people who visit websites that are very liberal or very conservative are just as likely to visit completely mainstream media sites as the typical internet user. In short, they do not find much evidence of segregation online.  However, they show that ideological segregation is still higher than most offline news consumption.

Gentzkow’s paper “Valuing New Goods in a Model with Complementarity: Online Newspapers,” (American Economic Review, 2007) examines the question of whether online news media and traditional paper media are substitutes or complements for consumers.  This potentially has important consequences for firms in the industry, but also for the question of how consumers will educate themselves about current events in the future. It also contributes to the literature on estimating the impact of new goods.  Previous discrete choice techniques in that literature implicitly assume that new goods are substitutes for existing goods.  In order to examine this question, Gentzkow extends existing discrete choice demand estimation techniques to allow for the possibility that bundles of goods are complements.  He finds clear evidence that print and online papers are substitutes.  His model reveals that the positive relationship between their consumption in the raw data is an artifact of consumer heterogeneity.  He also finds substantial welfare benefits from the introduction of free online newspapers.

Gentzkow’s 2013 working paper “Competition and Ideological Diversity: Historical Evidence from U.S. Newspapers” (jointly authored with Jesse Shapiro and Michael Sinkinson) analyzes the development of the U.S. newspaper industry and the historical effect newspapers have had on the US political system. The paper uses historical data to estimate a structural model of newspaper preferences and the environment in which they operate. This paper shows great data hustle to compile a relatively complete set of records of newspaper entry and exit and merge it with demographic and political data in order to answer important questions about what has shaped the nature of news media over a long period of time.

A second set of papers looks at the impact of television on society from several perspectives.  “Television and Voter Turnout” (Quarterly Journal of Economics, 2006) measures the effect of television on voter turnout by exploiting the variation in the time at which television was introduced in various regions of the US during the 1940s and 1950s. Gentzkow shows that a significant fraction of the reduction in voter turnout over the last century, particularly in local elections, can be explained by the introduction and the increased penetration of television. He argues that the introduction of television caused a substitution away from other media with more political coverage which then led to a decline in voting. Gentzkow presents empirical evidence that the entry of television in a market coincided with sharp drops in consumption of newspapers and radio and in political knowledge as measured by election surveys.

In “Preschool Television Viewing and Adolescent Test Scores: Historical Evidence From The Coleman Study” (Quarterly Journal of Economics, 2008) Gentzkow and Shapiro examine the impact of television on test scores using data from the “Coleman study.”  To identify the causal effect of television, the paper compares children of different ages at the time that television was introduced.  The analysis shows that television viewing did not have a negative impact on children.  The finding can be more easily interpreted when broken out by family situation: the impacts are most positive on underprivileged children who perhaps had a lower opportunity cost of their time.

A third set of papers look at questions of persuasion.  In “Media Bias and Reputation” (jointly authored with Jesse Shapiro), published in the Journal of Political Economy in 2006, the authors highlight the incentives of news outlets to incorporate an ideological slant.  The main idea is that Bayesian consumers will update positively about an outlet’s quality if the story conforms to her viewpoints.

With Emir Kamineca, Gentzkow has authored a series of very nice applied theory papers that tackle the question of how, in a game where a sender communicates private information to a receiver, a sender might choose to package information that they communicate in order to influence how a receiver behaves.  The model in “Bayesian Persuasion” (American Economic Review, 2011) assumes that the sender tells the truth, but shows that how the sender structures the space of signals that are possible to communicate affects outcomes.  In the real world, this might correspond to the sender designing an experiment to learn some information, or investing in getting certain types of data.  The authors find that a closer alignment of objectives between the sender and receiver does not necessarily lead to more informative communication, because what matters to the sender’s choice of possible signals is what structure is most effective at influencing the receiver’s actions.  The paper derives a number of comparative statics predictions and applies them to various real-world settings.

In a follow-on paper (“Competition in Persuasion,” Working Paper, 2012) Gentzkow and Kamineca study whether competition among senders increases the amount of information revealed. Although it might seem that this would be an intractable problem with lots of competing effects, the surprising finding is that more competition cannot decrease the information communicated.  A third paper by the same authors (“Disclosure of Endogenous Information,” Working Paper, 2012) studies the effects of disclosure requirements in this kind of environment.  The model has senders choosing how much to spend on acquiring more precise information.  The paper contrasts a world where players have exogenously specified information structures, and those where the senders can choose how much information to collect.  The main result is that disclosure requirements, which force the seller to reveal the results of his experiments, have no effect when information acquisition is endogenous: endogenously chosen information is always revealed.

Finally, (“The Evolution of Brand Preference: Evidence from Migration,” American Economic Review, 2012, jointly authored with Bart Bronnenberg and Jean-Pierre Dube) looks at advertising, another setting for understanding persuasion.  The paper explores the origins of brand preference. It is well known that consumers appear to have a high willingness to pay for particular brands, even when the alternatives seem similar. Previous research also shows striking regional differences in brand preference (e.g. Hellmans in the South but Miracle Whip in the North). The paper combines consumer panel data from Neilsen with data on consumer origins.  The paper focuses on consumers who move between states.  It first demonstrates that consumers have brand shares that are predictable by the current and birth states.  To do this, the authors construct a measure of the deviation of a migrant consumer’s purchase behavior from the mean consumer in the current state and regress it on measures of decades since move. They demonstrate an “on impact” effect of moving to a different state followed by a slow decay in consumers’ propensity to purchase the home state brands.   The “on impact” effect is attributed to supply-side factors such as price differentials, while the slow decay is attributable to brand preference.   They examine the speed of adoption of highly advertised/non highly advertised and highly visible/nonvisible consumption products.  Highly visible consumption products are products where the brand is socially visible at the time of consumption (yes for chips, no for toothpaste).  They find that advertising-intensive products have a significantly longer decay upon move, suggesting a brand capital effect.  They find that this brand capital effect is most pronounced for socially visible consumption items.

In summary, Gentzkow is a productive young economist who applies frontier methods in empirics and theory to an important set of questions. His skills span the full range of the discipline.  He has been a pioneer in the area of media economics, defining questions appropriate to the changing media landscape.  His work is creative without sacrificing quality.   He has established himself as a role model in both substance and execution.

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Tapping the Brakes: Are Less Active Markets Safer and Better for the Economy?

From Joe Stiglitz and summarized by Felix Salmon: Continue reading

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The Euro and the Geography of International Debt Flows

From Galina Hale and Maurice Obstfeld:

Greater financial integration between core and peripheral EMU members had an effect on both sets of countries. Lower interest rates allowed peripheral countries to run bigger deficits, which inflated their economies by allowing credit booms. Core EMU countries took on extra foreign leverage to expose themselves to the peripherals. The result has been asset-price bubbles and collapses in some of the peripheral countries, area-wide banking crisis, and sovereign debt problems. We analyze the geography of international debt flows using multiple data sources and provide evidence that after the euro’s introduction, Core EMU countries increased their borrowing from outside of EMU and their lending to the EMU periphery.

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Weekend Links: Understanding Piketty, Falling Interest Rates, Secular Stagnation, etc

  1. Brad Delong has a great post that provides an analytical framework for understanding the historical narrative in Piketty’s new book.
  2. Barry Eichengreen has a nice piece on declining interest rates
  3. Larry Summers gave a talk at INET (starts at 45 min and goes to 1:38 or so) with some especially interesting hypotheses about the changing structure of investment (from GE’s high capital investment model to Google’s abundance of cash) and reflections on the agriculture transition (around 1:21) and the associated difficulties with large shifts in the industrial composition of employment.

 

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Banks as Patient Fixed Income Investors

From Sam Hanson, Andrei Shleifer, Jeremy Stein, and Robert Vishny:

We examine the business model of traditional commercial banks in the context of their co- existence with shadow banks. While both types of intermediaries create safe “money-like” claims, they go about this in very different ways. Traditional banks create safe claims with a combination of costly equity capital and fixed income assets that allows their depositors to remain “sleepy”: they do not have to pay attention to transient fluctuations in the mark-to-market value of bank assets. In contrast, shadow banks create safe claims by giving their investors an early exit option that allows them to seize collateral and liquidate it at the first sign of trouble. Thus traditional banks have a stable source of cheap funding, while shadow banks are subject to runs and fire-sale losses. These different funding models in turn influence the kinds of assets that traditional banks and shadow banks hold in equilibrium: traditional banks have a comparative advantage at holding fixed-income assets that have only modest fundamental risk, but are relatively illiquid and have substantial transitory price volatility.

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Inputs in the Production of Early-childhood Human Capital: Evidence from Head Start

From Chris Walters:

Studies of small-scale “model” early-childhood programs show that high-quality preschool can have transformative effects on human capital and economic outcomes. Evidence on the Head Start program is more mixed. Inputs and practices vary widely across Head Start centers, however, and little is known about variation in effectiveness within Head Start. This paper uses data from a multi-site randomized evaluation to quantify and explain variation in effectiveness across Head Start childcare centers. I answer two questions: (1) Is there meaningful variation in short-run effectiveness across Head Start programs? and (2) Is variation in Head Start effectiveness related to observed inputs? To answer the first question, I develop an empirical Bayes instrumental variables procedure that measures variation in local average treatment effects (LATE), accounting for non-compliance with experimental assignments. I estimate that the cross-center standard deviation of cognitive effects is 0.3 test score standard deviations, which is substantially larger than typical estimates of variation in teacher or school effectiveness. Next, I assess the role of inputs in generating this variation, focusing on inputs commonly cited as drivers of the success of small-scale model programs. My results show that Head Start centers offering full-day service boost cognitive skills more than other centers, while Head Start centers offering frequent home visiting are especially effective at raising non-cognitive skills. Other key inputs, including the High/Scope curriculum, teacher education and certification, and class size, are not associated with increased effectiveness in Head Start. Together, observed inputs explain a small share of the variation in Head Start effectiveness. These findings suggest that replicating the effects of successful programs may be difficult, as the factors responsible for their success are largely unidentified.

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A Model of Secular Stagnation

From two of my favorite macroeconomists, Gauti Eggertsson and  Neil Mehrotra:

In this paper we propose a simple overlapping generations New Keynesian model in which a permanent (or very persistent) slump is possible without any self-correcting force to full employment. The trigger for the slump is a deleveraging shock which can create an oversupply of savings. Other forces that work in the same direction and can both create or exacerbate the problem are a drop in population growth and an increase in income inequality. High savings, in turn, may require a permanently negative real interest rate. In contrast to earlier work on deleveraging, our model does not feature a strong self-correcting force back to full employment in the long-run, absent policy actions. Successful policy actions include, among others, a permanent increase in inflation and a permanent increase in government spending. We also establish conditions under which an income redistribution can increase demand. Policies such as committing to keep nominal interest rates low or temporary government spending, however, are less powerful than in models with temporary slumps. Our model sheds light on the long persistence of the Japanese crisis, the Great Depression, and the slow recovery out of the Great Recession.

HT: Paul Krugman

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