English Indices of Deprivation (IoD 2025)
The Indices of Deprivation provide a relative measure of small-area deprivation across England. Open Road Risk uses three deprivation deciles as contextual predictors joined at LSOA level. They describe the area a road link passes through, not the road itself, and are not interpreted causally.
Source
- Publisher: Ministry of Housing, Communities and Local Government (MHCLG), English Indices of Deprivation 2025, released 30 October 2025.
- Licence: Open Government Licence v3.0.
- Geography: Lower-layer Super Output Area (LSOA), 33,755 areas in England, each ~1,000–3,000 residents.
- Edition note: IoD 2025 keeps the 2019 domain structure and weighting but refreshes indicators (e.g. the Indoors sub-domain now uses an EPC-based energy efficiency indicator in place of “houses without central heating”). Decile values are therefore not directly comparable to 2019.
Features used
| Feature | Source measure | Direction |
|---|---|---|
imd_decile |
Overall Index of Multiple Deprivation decile | 1 = most deprived, 10 = least deprived |
imd_crime_decile |
Crime domain decile | as above |
imd_living_indoor_decile |
Living Environment Indoors sub-domain decile | as above |
Deciles run 1 (most deprived) to 10 (least deprived), so a negative model coefficient means less-deprived areas have a lower predicted collision rate, holding other features fixed. Live coefficients and incidence-rate ratios are on the Stage 2 collision model page.
Why the Indoors sub-domain, not the full Living Environment domain
The Living Environment domain has two sub-domains. The Outdoors sub-domain is built from air quality and road traffic accidents involving injury to pedestrians and cyclists. Using it — or the combined domain — as a predictor of collision risk would feed a function of the outcome back in as an input, inflating apparent performance without reflecting any real predictive signal.
The model therefore uses the Indoors sub-domain only (housing condition and energy efficiency), which carries no road-safety construction. The overall IMD decile is retained because road-traffic accidents are one indicator among 55 across seven domains and contribute negligibly to the headline index, but this is a judgement call rather than a guarantee of zero contamination.
Coverage and missingness
- England only. Welsh LSOAs (and the Welsh-side edges of the study area) have no IoD 2025 value. Scotland and Wales publish separate, non-comparable indices.
- Links that fail to join to an English LSOA — Welsh edges, unmatched geometry — receive imputed decile values, flagged with an
_imputedsuffix in the model feature set so the imputation is visible rather than silent. - Because deciles are a relative national ranking, they cannot be compared across editions or against the Welsh/Scottish indices.
Provenance
All three deciles are read directly from MHCLG File 7 (File_7_IoD2025_All_Ranks_Scores_Deciles_Population_Denominators.csv), which carries the Indoors Sub-domain Decile column alongside the overall IMD and domain deciles — so the Indoors decile is taken as published, not re-derived from a sub-domain score. The feature builder (src/road_risk/features/network.py) fails fast if that column is absent, so a silently missing decile cannot pass through unnoticed.
Role in the pipeline
These are area-context predictors, in the same tier as OS Terrain 50 grade and ONS Rural-Urban Classification — they sit alongside exposure and road-geometry features in Stage 2, not in the exposure model. They are contextual signal at LSOA resolution, not evidence that deprivation causes road risk.