One of the human error engineering tools is the analysis method to determine the probability of various types of events and injury in an organization. This tool can provide invaluable insight in:
- High risk events or injury
- Important factors affecting risk
- Root causes of past events and injury
- Cost-effective ways to prevent events and injury
PII has used this tool extensively to prevent high risk events or injuries before they occur. Before the availability of this tool, high risk events or injuries are corrected only after extensive root cause analysis of past occurrences.
The following figure shows the human error engineering analysis to determine the probability of a given type of event or injury.
The event or injury probability is a product of the triggering event, the failure rates for LOPs, and the ratio of injury (or event) probability to error probability.
PII’s field research found that, for a typical organization, most types of injuries or events (~50%) are prevented by two layers of protections (LOPs). Events or injuries (~30%) that have minor consequences are usually prevented by one LOP. Events or injuries that have serious consequences (~20%) are usually prevented by three LOPs.
