# Contract (F2-smoke-01)

• Question: linear association of y with x in a firm panel. Estimand: population linear-projection slope β in y = α + βx + ε (also α). Meaningful under: obs independent across firms, arbitrary dependence within firm; finite second moments; enough clusters for asymptotics (G=50 here). β is a projection coefficient, not causal.
• Uncertainty: firm-clustered (CR1) SE; naive homoskedastic OLS SE as baseline.
• 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.
• Info rule: only data/panel.csv.
• Invalid/impossible if: data missing/unreadable, firm_id missing, too few clusters (e.g. <~10) for cluster-robust inference, x constant.