# Contract (F2-smoke-01)

• Question: linear association of y with x in a firm panel, with uncertainty that allows dependence within firms (independent across firms).
• Estimand: population linear-projection slope beta in y = alpha + beta x + e (and intercept alpha). Meaningful under: i.i.d. sampling of firms, finite second moments, Var(x)>0; no causal interpretation implied.
• Estimator: pooled OLS with intercept; baseline SE = conventional homoskedastic; main SE = cluster-robust by firm_id (CR1); 95% CI = beta_hat ± t_{G-1,0.975}·se_cluster.
• Outputs: out/results.json (task_id, beta_hat, alpha_hat, se_ols, se_cluster, beta_ci_low, beta_ci_high, n_analysed, n_clusters, feasibility, feasibility_reason, data_issues, n_input_rows, random_seed), out/report.md (Question; Data and exclusions; Method; Results; Uncertainty; Limitations and open issues), out/analysis.py, out/claims.json.
• Information rule: only data/panel.csv.
• Invalid/impossible if: file missing/unreadable, no firm_id, too few clusters (e.g. <~10) for cluster asymptotics, x constant.