Test graduate students' ability to apply difference-in-differences methods to estimate economic impacts of policy interventions using panel data. Assess competence in specifying models (two-way fixed effects, dynamic/event-study designs), articulating and testing identification assumptions (parallel trends, no anticipatory effects), addressing staggered adoption and heterogeneous treatment effects, choosing appropriate clustering and inference, conducting pre-trend/placebo and robustness checks, and interpreting coefficients and economic magnitudes. Expect students to outline estimation steps, identify potential biases (e.g., negative weights, time-varying confounders), and propose corrective approaches (alternative estimators, cohort/event-study methods, weighting) for a typical panel dataset.