In safety management, numbers matter.
Something happens on the floor or on the job site, which qualifies as a recordable, which contributes to a rate. Over time, small changes in rates can help indicate whether a program is moving in the right direction or the wrong one.
The statistical perspective is powerful, and the story these rates tell is important. But a growing body of evidence suggests that the story told by one commonly reported rate is not complete. The real picture may be less rosy than it seems.
If we want to continue making progress in improving the safety outcomes that matter most, fresh eyes and fresh thinking may be needed. It all comes back to the rates.
Incident Rates and the Heinrich Pyramid
Many organizations use the total recordable incident rate (TRIR) as an EHS performance indicator, allowing benchmarking and comparisons within and across industries. But the TRIR lumps together incidents that vary widely in their severity, since any medical treatment and days away from work are enough to qualify an incident as a recordable according to OSHA's recordkeeping requirements.
The thinking behind this "all incidents matter" approach goes back to 1931, when Herbert Heinrich published a pioneering book on industrial safety based on his research in the insurance industry. He was one of the first to bring a statistical view to the problem of safety.
Heinrich's view was that for every safety incident, it was just a matter of chance, a roll of the dice, that determined whether the outcome would be a close call, a fatality, or something in between. He stated that for every 330 incidents, 300 would be near misses resulting in no injury, 29 would result in minor injuries, and one would result in serious injury. This relationship is called the Heinrich pyramid or the Heinrich triangle.