# Contract (F2-smoke-01)
- Question: linear association between y and x in a firm panel, with uncertainty valid under within-firm dependence (independence across firms only).
- Estimand: population linear-projection slope beta in y = alpha + beta x + e (plus intercept alpha). Meaningful as a projection coefficient (no causal claim); clustered inference requires independence across firms and a reasonably large number of clusters.
- 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.
- Invalidity: missing/garbled columns, too few clusters for cluster-robust inference, no variation in x.