arXiv subjects

Johannes Stroebel

Publications and source records attributed to Johannes Stroebel.

3 recordsLinked to original sources

arXiv2020

The geographic spread of COVID-19 correlates with the structure of social networks as measured by Facebook

We use aggregated data from Facebook to show that COVID-19 is more likely to spread between regions with stronger social network connections. Areas with more social ties to two early COVID-19 "hotspots" (Westchester County, NY, in the U.S. and Lodi province in Italy) generally had more confirmed COVID-19 cases by the end of March. These relationships hold after controlling for geographic distance to the hotspots as well as the population density and demographics of the regions. As the pandemic progressed in the U.S., a county's social proximity to recent COVID-19 cases and deaths predicts future outbreaks over and above physical proximity and demographics. In part due to its broad coverage, social connectedness data provides additional predictive power to measures based on smartphone location or online search data. These results suggest that data from online social networks can be useful to epidemiologists and others hoping to forecast the spread of communicable diseases such as COVID-19.

physics.soc-ph↗

arXiv2020

Online Appendix & Additional Results for The Determinants of Social Connectedness in Europe

In this online appendix we provide additional information and analyses to support "The Determinants of Social Connectedness in Europe." We include a number of case studies illustrating how language, history, and other factors have shaped European social networks. We also look at the effects of social connectedness. Our results provide empirical support for theoretical models that suggest social networks play an important role in individuals' travel decisions. We study variation in the degree of connectedness of regions to other European countries, finding a negative correlation between Euroscepticism and greater levels of international connection.

econ.GN↗

arXiv2020

Inside the Mind of a Stock Market Crash

We analyze how investor expectations about economic growth and stock returns changed during the February-March 2020 stock market crash induced by the COVID-19 pandemic, as well as during the subsequent partial stock market recovery. We surveyed retail investors who are clients of Vanguard at three points in time: (i) on February 11-12, around the all-time stock market high, (ii) on March 11-12, after the stock market had collapsed by over 20\%, and (iii) on April 16-17, after the market had rallied 25\% from its lowest point. Following the crash, the average investor turned more pessimistic about the short-run performance of both the stock market and the real economy. Investors also perceived higher probabilities of both further extreme stock market declines and large declines in short-run real economic activity. In contrast, investor expectations about long-run (10-year) economic and stock market outcomes remained largely unchanged, and, if anything, improved. Disagreement among investors about economic and stock market outcomes also increased substantially following the stock market crash, with the disagreement persisting through the partial market recovery. Those respondents who were the most optimistic in February saw the largest decline in expectations, and sold the most equity. Those respondents who were the most pessimistic in February largely left their portfolios unchanged during and after the crash.

econ.GN↗