Serious injuries are claimed to sit atop a fixed ratio of minor injuries and near misses.
The original data are lost and the fixed ratios are widely disputed. It remains embedded in safety practice, which is a problem, since focusing on minor-injury counts diverts attention from low-frequency catastrophic risk.
In practice
- A site that reports 400 near misses and no serious injuries treats the record as safety, and the ratio says nothing about the rare catastrophic risk.
- A firm counting minor incidents in a chemical plant is measuring the wrong tail entirely, since the process safety risk is uncorrelated with slips and trips.
- Possible explanations
- The explanation offered is a fixed pyramid of causes, in which the same unsafe acts produce many minor incidents and occasionally a fatal one, so counting the base predicts the top.
- In its favour
- Near-miss reporting, which the triangle popularised, is genuinely useful, and some hazards do produce graded outcomes from the same mechanism.
- Against it
- The original data are lost, the fixed ratios are widely disputed, and modern safety research finds that serious accidents often have different causes from minor ones, so driving down minor-injury counts can leave the fatal risks untouched.
- Standing
- The original data are lost and the fixed ratios are widely disputed; still embedded in safety practice.
- Subject
- Risk & Reliability
- Essay
- How accidents actually happen