Category: Risk management frameworks · Reviewed by Tim Roche, Director · PI & Commercial · Last reviewed
A risk matrix (also: consequence/probability matrix) is the underlying numerical or ordinal grid used to score risks for a heat map. Where the heat map is the chart, the matrix is the scoring rubric.
Impact bands should be expressed in units relevant to the firm:
| Band | Financial | Reputational | Regulatory | People |
|---|---|---|---|---|
| 1 — Insignificant | <£10k | Internal only | No notification | No injury |
| 2 — Minor | £10k–£100k | Local press | Notifiable, no fine | First aid |
| 3 — Moderate | £100k–£1m | National press | Fine < £100k | RIDDOR injury |
| 4 — Major | £1m–£10m | Multi-day press | Fine £100k–£1m | Serious injury |
| 5 — Catastrophic | >£10m | Brand-damaging | Fine > £1m, licence at risk | Fatality |
Likelihood bands should be time-bounded probabilities, not vague labels:
| Band | Annual probability | Approx return period |
|---|---|---|
| 1 — Rare | <1% | >100 years |
| 2 — Unlikely | 1–5% | 20–100 years |
| 3 — Possible | 5–25% | 4–20 years |
| 4 — Likely | 25–75% | 1.3–4 years |
| 5 — Almost certain | >75% | <1.3 years |
Some firms multiply scores (likelihood × impact); others use a look-up matrix where the colour for each cell is set independently. The look-up approach avoids the misleading arithmetic implied by ordinal multiplication.
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