Fit Difference-in-Differences Models with Staggered Interventions // Fits linear difference-in-differences models in scenarios where intervention roll-outs are staggered over time. The package implements a version of an approach proposed by Sun and Abraham (2021) doi:10.1016/j.jeconom.2020.09.006 to estimate cohort- and time-since-treatment specific difference-in- differences parameters, and it provides convenience functions both for specifying the model and for flexibly aggregating coefficients to answer a variety of research questions.