# Risk-estimation data sources & licenses

Provenance for the probability (W) / avoidance (P) tiers in `risk_estimation.go`
(`contactModeTable`). We do **not** vendor any raw dataset — only the small
aggregate facts used as anchors plus our own calibrated tiers live in code.

## What we use and how

The tiers are derived in two steps:

1. **Anchor** — the *relative ordering* of injury contact modes from public,
   permissively-licensed occupational-accident statistics (which mechanisms are
   more vs. less frequent).
2. **Calibrate** — adjust the tier *values* to our own ground-truth corpus
   (the professional's W/P per mode). Well-sampled modes are set to the GT mean;
   sparse modes use conservative defaults (no overfitting to a 2-GT sample).

The numbers in code are therefore **ours**, not a copy of any dataset, and they
do **not** reproduce any standard's risk-graph table, decision tree or matrix.

## Primary source — Eurostat ESAW

- **Dataset:** European Statistics on Accidents at Work (ESAW), contact mode of injury.
- **License:** **CC BY 4.0** — commercial and non-commercial reuse permitted,
  source acknowledgement required.
- **Attribution string:** `Source: Eurostat (ESAW), CC BY 4.0` — surface this in
  any generated risk-assessment export that shows engine risk numbers.
- **URL:** https://ec.europa.eu/eurostat/statistics-explained/index.php/Accidents_at_work_-_statistics_on_causes_and_circumstances
- **Aggregate facts used (anchor only):** contact-mode shares of accidents at
  work, e.g. impact with stationary object ~24%, struck by moving object ~13%
  (non-fatal) / ~24% (fatal), trapped/crushed ~14% (fatal), contact with sharp
  agent ~15%. Retrieved 2026-06.

## Acceptable supplements

- **US BLS / OSHA** (Bureau of Labor Statistics, occupational injuries) — **U.S.
  Government work, public domain**; free for any use.
- **UK HSE** (RIDDOR / kinds-of-accident) — **Open Government Licence v3**;
  commercial reuse with attribution.

## Explicitly excluded

- **DGUV statistics** — terms grant only editorial use and forbid modification
  / re-licensing; **unsuitable for a commercial product**. Not used.
- **DIN / Beuth / ISO / IEC standards** (e.g. risk-graph tables, parameter
  decision trees, SIL/PL matrices) — copyrighted; **not reproduced or
  re-implemented**. Our model uses only the universal, non-protectable risk
  *dimensions* (severity, frequency, probability, avoidance).

## Maintenance

When a tier in `contactModeTable` changes, record the source figure and the GT
calibration basis here. Add this file to the repository SBOM / license register
alongside software dependencies.