> ## 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.

# Which part of the lap is the driver finding time in?

> The lap decomposition applied to each of the three timing sectors separately, allocating physics components by sector time share so sectors sum to the lap.

A lap delta is one number, but the time is found in different places a strong sector one, a weak sector three. Sector decomposition applies the lap-level residual identity to each of the three timing sectors separately, allocating the physics components in proportion to each sector's share of the lap. It tells you not just *how much* faster a driver was, but *where* on the track.

## What it shows

Each sector carries its own decomposition:

* **Pace delta**: the driver's average sector time minus the rolling 7-lap field median sector time for that sector and lap number.
* **Skill residual**: the portion of the pace delta not explained by the physics components (fuel, tyres, ambient, constructor, dirty air) the driving contribution within that sector.
* **Total explained**: the sum of the six physics components allocated to the sector. A large value means external factors, not driving style, dominated the delta.
* **Consistency**: the within-race standard deviation of the skill residual for that driver–sector pair. Lower = more repeatable.

All physics components are allocated using `sector_time / lap_time` as the weight, which preserves the **sector sum = lap total** identity.

<Note>
  Because allocation is proportional, the three sectors' components add back up to the full-lap decomposition you can read a sector in isolation without breaking the identity.
</Note>

## How to use it

1. **Select a race and driver** from the filter bar; the three sector decompositions load.
2. **Compare skill residual across sectors** to find where the driver genuinely gains or loses.
3. **Check total explained** a big delta with a big explained component is the car or conditions, not the driver.
4. **Read consistency** to separate a one-off fast sector from a repeatable strength.

## Reading the signal correctly

Sector time is a coarse proxy for "where on track" a sector can contain several corner types, so a strong sector-two residual localises but does not pinpoint the gain. The allocation is **proportional**, which assumes physics effects scale with time share; this holds well on average but blurs corner-specific effects.

<Warning>
  The rolling 7-lap field median is noisier per sector than per lap (sector times are shorter and more variable). Treat single-sector residuals as lower-confidence than the full-lap figure. See the [decomposition limitations](/decomposition/limitations).
</Warning>

## Data source

The chart queries `int_sector_residual_decomposed` via DuckDB-Wasm in the browser, for a single race.

| Column                     | Meaning                                              |
| -------------------------- | ---------------------------------------------------- |
| `sector_pace_delta_s`      | Sector time vs rolling 7-lap field median            |
| `sector_skill_residual_s`  | The unexplained (driving) part of the sector delta   |
| `sector_total_explained_s` | The six physics components allocated to the sector   |
| `sector_skill_stddev_s`    | Within-race consistency of the sector skill residual |

This is a **single-race** view across **2018–2024** data.

For the full model definition, see the [`int_sector_residual_decomposed` reference](/reference/models/int/int_sector_residual_decomposed).