# Contract — F2-smoke-01

Question: linear association between y and x in a firm panel, with uncertainty valid under within-firm dependence (common firm shock), independence across firms. Estimand: population linear-projection slope β in y = α + βx + ε (and α). Meaningful as a projection coefficient (no causal claim); clustered inference valid when clusters (firms) are independent and number of clusters is reasonably large. 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 rules: only data/panel.csv. Invalidity/impossibility: missing/unusable columns, no variation in x, too few clusters (e.g. <2) for cluster SE; results invalid if within-firm dependence ignored for the reported CI.