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...

We introduce a new measure of social connectedness between U.S. county-pairs, as well as between U.S. counties and foreign countries. Our measure, which we call the "Social Connectedness Index" (SCI), is based on the number of friendship links on Facebook, the world's largest online social...

We use anonymized data from Facebook to construct a new measure of the pairwise social connectedness between 180 countries and 332 European regions. We find that two countries trade more with each other when they are more socially connected and when they share social connections with a similar...

This paper presents market-based evidence that President Trump influences expectations about monetary policy. We use tick-by-tick fed funds futures data and a collection of Trump tweets criticizing the conduct of monetary policy and consistently advocating that the Fed lower interest rates....

We study the causal effect of social media on ethnic hate crimes and xenophobic attitudes in Russia using quasi-exogenous variation in social media penetration across cities. Higher penetration of social media led to more ethnic hate crimes, but only in cities with a high pre-existing level of...

GDP and derived metrics (e.g., productivity) have been central to understanding economic progress and well-being. In principle, the change in consumer surplus (compensating expenditure) provides a superior, and more direct, measure of the change in well-being, especially for digital goods, but...

We study how the structure of social media networks and the presence of fake news might affect the degree of misinformation and polarization in a society. For that, we analyze a dynamic model of opinion exchange in which individuals have imperfect information about the true state of the world...