> ## 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.

# driver_isolation_reliability

> The confidence columns every driver-isolation rating carries (WI-16a), at any grain.

The confidence columns every driver-isolation rating carries (WI-16a), at any grain. Given a raw rating, its standard error, the signal variance tau^2 of that rating at that grain and season, and the rating's method score and grade (from the driver\_isolation\_method\_scores seed), emits four columns: \<prefix>\_lambda          reliability tau^2 / (tau^2 + SE^2), in \[0, 1] \<prefix>\_shrunk\_gain\_s   lambda \* raw: the normal-normal posterior mean with prior mean 0 (every rating is field- or peer-centred). Equivalent to bayesian\_shrinkage() with prior\_weight = sigma\_w^2 / tau^2 in effective laps when SE^2 = sigma\_w^2 / n\_eff. \<prefix>\_confidence\_pct  ROUND(100 \* lambda \* method\_score); NULL without a lambda or before the method is validated. A declared policy, not an estimated quantity. \<prefix>\_trust\_label     'unvalidated' (method score NULL), 'suppress' (grade F, no lambda, or confidence \< 25), 'thin' (25-50), 'indicative' (50-75), 'solid' (>= 75); NULL when there is no raw value. Floors come before this: a raw value is already NULL below its sample floor, so the shrinkage only handles the range between "just enough" and "plenty".

## Signature

```sql theme={null}
{{ driver_isolation_reliability(prefix, raw, se, tau2, method_score, method_grade) }}
```

## Arguments

| Argument | Description |
| - | - |
| `prefix` | column-name prefix, e.g. 'pure\_skill\_5lap' |
| `raw` | expression for the raw rating (s/lap, positive = faster) |
| `se` | expression for its standard error (s/lap) |
| `tau2` | expression for the signal variance (s^2) |
| `method_score` | expression for the rating's method score in \[0, 1], or NULL |
| `method_grade` | expression for the rating's grade (A/B/C/F, or 'unvalidated') |

## Usage

```sql theme={null}
SELECT {{ driver_isolation_reliability('pure_skill', 'pure_raw', 'pure_se',
                                           'tau.pure_tau2', 'ms.method_score',
                                           'ms.grade') }}
```


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