Online sources sometimes publish information that is false or intentionally misleading. We study the role of social networks and advertising on social networks in the dissemination of false news stories about childhood vaccines. We document that anti-vaccine Facebook groups disseminate false...

COVID-19 vaccines are widely available in wealthy countries, yet many people remain unvaccinated. Understanding the effectiveness -- or lack thereof -- of popular vaccination campaign strategies is therefore critical. In this paper, we report results from two studies that tested strategies...

Third-party cookies and related 'offsite' tracking technologies are frequently used to share user data across applications in support of ad delivery. These data are viewed as highly valuable for online advertisers, but their usage faces increasing headwinds. In this paper, we quantify the...

Platform marketplaces can potentially steer buyers to certain sellers by recommending or guaranteeing those sellers. Money-back guarantees--which create a direct financial stake for the platform in seller performance--might be particularly effective at steering, as they align buyer and platform...

This paper examines a model in which advertisers bid for "sponsored-link" positions on a search engine. The value advertisers derive from each position is endogenized as coming from sales to a population of consumers who make rational inferences about firm qualities and search optimally....

We investigate the "generalized second price" auction (GSP), a new mechanism which is used by search engines to sell online advertising that most Internet users encounter daily. GSP is tailored to its unique environment, and neither the mechanism nor the environment have previously been studied...

A model is developed where traditional and digital advertising finance the provision of free media goods and affect price competition. The economy is not efficient. Media goods are under provided. Additionally, there is too much advertising when ads cannot be perfectly directed toward potential...

Ad blockers allow Internet users to obtain information without generating ad revenue for site owners; and by 2016 they were used by roughly a quarter of site visitors. Given the ad-supported nature of much of the web, ad blocking poses a threat to site revenue and, if revenue losses undermine...

Watching TV and other forms of media consumption represent, after sleeping and working, the main activity that adults perform in developed countries. We present a dynamic theory of commercial broadcasting where the media trade utility-raising goods (programs, information, and services) with...

Search frictions can explain why the "law of one price" fails in retail markets and why even firms selling commodity products have pricing power. In online commerce, physical search costs are low, yet price dispersion is common. We use browsing data from eBay to estimate a model of consumer...