Assess students' ability to design, estimate, and interpret causal effects of policy changes on firm-level outcomes using difference-in-differences and instrumental variables. The quiz will test identification (parallel trends, instrument relevance/exogeneity), model specification (two‑way fixed effects, event‑study, choosing controls), estimation and inference (clustered SEs, first‑stage F, weak instrument diagnostics), robustness checks (placebo/falsification, heterogeneous effects), and clear interpretation of results and limitations in panel data applications.