The eighth “One World webinar” organized by YoungStatS will take place on December 15th, 2021. The difference-in-differences design is a quasi-experimental identification strategy for estimating causal effects which has become the single most popular research design in the quantitative social sciences, and as such, it merits careful study by researchers everywhere. It is also a flourishing field of present research in econometrics. Selected younger researchers active in the area will present their recent contributions on this topic. Speakers: Clément de Chaisemartin, Sciences Po, Paris, France Jonathan Roth, Brown University, USA Brantly Callaway, University of Georgia, USA Lihua Lei, Stanford University, USA Discussant: Prof. Pedro H.C. Sant’Anna, Microsoft and Vanderbilt University, USA The webinar is part of YoungStatS project of the Young Statisticians Europe initiative (FENStatS) supported by the Bernoulli Society for Mathematical Statistics and Probability and the Institute of Mathematical Statistics (IMS).