From the beginning of 2020, the whole world has been shaken by a contagious disease called Covid-19, its actual name being SARS-CoV-2. It first appeared in China, in Wuhan, Hubei Province, in December 2019, and the World Health Organization (WHO) was informed about it on the 31st of December...

Linear panel models, and the "event-study plots" that often accompany them, are popular tools for learning about policy effects. We discuss the construction of event-study plots and suggest ways to make them more informative. We examine the economic content of different possible identifying...