Severity rate

The severity rate is the metric that asks how bad the injuries are, not how many — the total days away from work divided by the number of recordable incidents. A TRIR of 3.0 tells you the frequency; the severity rate tells you whether those three incidents were cuts that needed a stitch or amputations that ended a career, and a program with a low frequency and a high severity is a different risk profile from one with a high frequency and a low severity. OSHA recordkeeping under 29 CFR 1904 counts the days away from work on the 300 log, and the severity rate is the number that surfaces the catastrophic-event risk a frequency metric can hide.

The severity rate is the companion to TRIR, not a replacement, and a program that reports only the frequency is reporting only half the picture. The trend that should worry leadership is the severity rate that rises while the TRIR falls — fewer incidents, but the ones that happen are worse — because that is the signature of a program that suppressed the minor injuries without addressing the serious-injury potential underneath. The leading indicators that predict a severity spike are the near-misses with serious potential, the SIF precursors, and the management-of-change gaps — the measures that move before the catastrophic event does. See TRIR, LTIR, and DART.