> ## Documentation Index
> Fetch the complete documentation index at: https://offthepace.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# int_constructor_car_fe_isolation

> Driver-isolation car term: a thin reader over data/fits/constructor_car_fe_isolation.parquet, fitted by fit_constructor_car_fe.py --panel isolation (mean y_s ~ 1 | driver_id + constructor_race on driver-race means of the pre-cliff Ω laps, separately in each era; fit_method constructor_car_fe_isolation_hdfe_v2), re-centred to a lap-weighted mean of zero inside each race.

<Note>Part of the [Skill](/transform/families/skill) family.</Note>

Driver-isolation car term: a thin reader over data/fits/constructor\_car\_fe\_isolation.parquet, fitted by fit\_constructor\_car\_fe.py --panel isolation (mean y\_s \~ 1 | driver\_id + constructor\_race on driver-race means of the pre-cliff Ω laps, separately in each era; fit\_method constructor\_car\_fe\_isolation\_hdfe\_v2), re-centred to a lap-weighted mean of zero inside each race. Fitted on the same scale as y\_s, unlike int\_constructor\_car\_fe (pace\_delta\_s, before compound and dirty air come out), so subtracting it does not take strategy and traffic out twice. There is no global-driver fallback: a team whose drivers drove for no other team in the era is an island ('unidentified', NULL), and a cell with only one of the team's drivers in the fit is 'not\_estimated' (NULL). Negative = faster. Leakage: a function of the residual trajectory; no ML-contract mart may depend on it (T48, ml/tests/test\_manifest\_contract.py). WI-16a, \_roadmap/\_fixes/wi/WI-16-cumulative-driver-isolation.md.

## Lineage

```mermaid theme={null}
flowchart LR
  int_constructor_car_fe_isolation --> int_driver_isolation_lap_pace
  style int_constructor_car_fe_isolation fill:#e40404,stroke:#e40404,color:#fff
```

## Overview

| Property | Value |
| - | - |
| Layer | `intermediate` |
| Family | [Skill](/transform/families/skill) |
| Contract enforced | No |
| Tags | `driver_isolation`, `constructor` |

**9 tests** [guard](/transform/ci/overview) this model  -  9 generic, 0 singular.

## Columns

| Column | Type | Nullable | Tests | Description |
| - | - | - | - | - |
| `constructor_car_fe_isolation_id` | | Yes | [`not_null`](/transform/ci/structural), [`unique`](/transform/ci/structural) | Surrogate PK = race\_year\_raceid\_constructorid. |
| `race_year` | | Yes | [`not_null`](/transform/ci/structural) | Season. |
| `race_id` | | Yes | [`not_null`](/transform/ci/structural) | FastF1 event id, e.g. 2021\_8. |
| `constructor_id` | | Yes | [`not_null`](/transform/ci/structural) | Constructor (stg\_laps.constructor\_id). |
| `era` | | Yes | [`not_null`](/transform/ci/structural) | Regulation era: pre\<era\_boundary> or post\<era\_boundary> (var era\_boundary, 2022). |
| `n_laps` | | Yes | [`not_null`](/transform/ci/structural) | Ω laps of this constructor in the race: the re-centring weight. |
| `car_fe_raw_s` | | Yes | | The fitted constructor×race FE before re-centring, s on the y\_s scale; NULL when not identified. |
| `car_iso_s` | | Yes | | Isolation car term, s, NEGATIVE = FASTER than the race's lap-weighted car (int\_constructor\_car\_fe\_isolation). NULL when not identified. |
| `car_term_source` | | Yes | [`not_null`](/transform/ci/structural), [`accepted_values`](/transform/ci/range-and-domain) | Where car\_iso\_s came from: driver\_id (fitted per-era), unidentified (multiple components in race), not\_estimated (pyfixest singleton), or no\_fit\_row (no row in the fit). |
| `race_components_n` | | Yes | | Connected components the race's constructor×race cells span under the driver key used; 1 = every car level in the race is comparable. |
| `connectivity_note` | | Yes | | The fit's per-era connected-set diagnostics and fallback decision. |
| `fit_method` | | Yes | | Provenance fit identifier (constructor\_car\_fe\_isolation\_hdfe\_v1). |
| `fit_timestamp` | | Yes | | Provenance UTC timestamp of the fit. |


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