iv_compare
Run multiple IV estimators on the same specification and compare estimates, confidence intervals, and first-stage F statistics to check instrument strength and sensitivity before reporting.
Instructions
Run several k-class / JIVE estimators on the same IV specification and return a one-row-per-method comparison DataFrame (estimate, SE, CI, first-stage F). Useful as a sensitivity sanity check before reporting. Assumptions: Instrument relevance (non-zero first stage); Exclusion restriction: the instrument affects the outcome only through the treatment; Independence/exogeneity of the instrument; for LATE, monotonicity (no defiers). Pre-conditions: An instrument plausibly affecting treatment, an endogenous treatment, and an outcome; A strong first stage (assess instrument strength before interpreting estimates). Failure modes: Weak first stage -- biased point estimates and unreliable conventional SEs -> Report first-stage F / effective F and use weak-IV-robust inference (Anderson-Rubin). Alternatives: sp.iv, sp.anderson_rubin_ci, sp.dml. Typical minimum N: 200.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| alpha | No | Significance level for confidence intervals and tests. | |
| detail | No | Payload depth: 'minimal' (~150 tokens) for sub-step calls where only the point estimate is needed; 'standard' (~1K tokens) for diagnostics + coefficient table; 'agent' (~2K tokens, default) adds violations / next_steps / suggested_functions so the LLM can plan its next call without another round-trip. | agent |
| formula | Yes | Model formula using patsy/R-style syntax. | |
| methods | No | methods parameter (tuple[str]). | |
| as_handle | No | If true, cache the fitted result on the server and return result_id + result_uri alongside the JSON payload so a subsequent tools/call can chain without re-running. | |
| data_path | Yes | Absolute path or URL to a data file. Supported: .csv / .tsv / .txt (delimited), .parquet / .pq, .feather / .arrow, .xlsx / .xls, .dta (Stata), .json / .jsonl. Schemes: file://, s3://, gs://, https://. | |
| result_id | No | Optional handle to a previously-fitted result (returned by an earlier call when as_handle=true). Tools that operate on a fitted object accept this in place of re-supplying data_path + columns. | |
| endog_name | No | Override endogenous-coefficient name lookup | |
| data_columns | No | Optional column projection. Parquet/Feather/Stata loaders honour this for fast partial reads. | |
| data_sample_n | No | Optional uniform random subsample size (seed=0, deterministic) — useful on huge panels. |
Output Schema
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||