We use the U.S. patent data merged with firm-level datasets to establish new facts about the role of mega firms in generating "novel patents"--innovations that introduce new combinations of technology components for the first time. While the importance of mega firms in novel patents had been...

We measure the individual and collective viewpoints of US Congress members on various economic policies by scraping their Twitter accounts. Tweets that criticize (support) a particular company are associated with a significant negative (positive) stock price reaction in a narrow time window...

During the COVID-19 epidemic, many health professionals started using mass communication on social media to relay critical information and persuade individuals to adopt preventative health behaviors. Our group of clinicians and nurses developed and recorded short video messages to encourage...

We study how social media affects election outcomes in the United States. We use variation in the number of Twitter users across counties induced by early adopters at the 2007 South by Southwest (SXSW) festival, a key event in Twitter's rise to popularity. We show that this variation is...

This paper studies the implications of attempts at "ethnic-affinity" profiling on Facebook that reflects users' engagement with content on Facebook. Profiling by ethnic-affinity is highly correlated with Census estimates of population race by geography. However, more users were profiled as...

We investigate whether Donald Trump's "Chinese Virus" tweets contributed to the rise of anti-Asian incidents. We find that the number of incidents spiked following Trump's initial "Chinese Virus" tweets and the subsequent dramatic rise in internet search activity for the phrase....

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...

Using a new comprehensive survey of adults in large U.S. media markets we show that minority and low-skill individuals, who are heavily exposed to shocks to the local economy, typically have stronger preferences for and stronger ex- posure to local news than high-skill and white individuals. At...

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...