Education & Standards · Explainer
Leading and lagging indicators: measuring safety before harm
Injury rates tell you what has already gone wrong. Leading indicators show whether the things that prevent harm are actually happening.
Most organisations track injury rates. They matter, but by the time they move, someone has been hurt. OSHA’s 2019 guide Using Leading Indicators to Improve Safety and Health Outcomes (OSHA 3970) explains the difference and how to choose better measures [1].
Definitions
OSHA describes lagging indicators as measures of the number or rate of injuries, illnesses and fatalities. Events that have already happened. Leading indicators are proactive, preventive and predictive measures that show how well safety and health activities are working and can flag problems before an incident occurs [1].
OSHA’s examples of leading indicators include the time it takes to respond to a safety hazard report, the percentage of workers who receive quarterly refresher training, and the number of trucks that have their brake pads replaced at a set mileage interval [1].
Good indicators are SMART
The guide recommends that leading indicators be Specific, Measurable, Accountable, Reasonable and Timely [1]. A useful test: if the number changed, would anyone do anything differently?
Calculating a lagging rate correctly
The US Bureau of Labor Statistics gives the incidence rate formula as the number of injuries and illnesses × 200,000, divided by employee hours worked. The 200,000 figure represents 100 full-time employees working 40 hours a week for 50 weeks, which allows comparison across organisations of different sizes [2]. In BLS’s worked example, 7 cases in 400,000 hours gives a rate of 3.5 [2].
Try it with the incident rate calculator.
Two sites each report an injury rate of zero for the quarter. At one, hazard reports are closed within two days on average and 95% of planned inspections were done. At the other, reports wait three weeks and half the inspections were skipped. The lagging number is identical; the leading indicators tell very different stories.
Watch for unintended effects
Any indicator tied to rewards can distort reporting. A falling injury rate is good news only if people are still reporting freely. Pair outcome measures with measures of reporting, follow-through and the quality of controls.
Count fewer things, and act on what you count. Three leading indicators that drive real conversations are worth more than a dashboard of thirty.
General educational material, not legal advice, a site-specific risk assessment or a work authorisation. Confirm current requirements in your jurisdiction and follow site procedures and competent advice.
References
- OSHA. Using Leading Indicators to Improve Safety and Health Outcomes (OSHA 3970, June 2019)United States
- US Bureau of Labor Statistics. How to compute your firm’s incidence rate for safety managementUnited States
All sources opened and checked on 30 October 2026. Requirements and guidance change; always consult the current version.
Downloads & tools
TOOLIncident rate calculatorCalculate recordable incidence rates using the BLS formula, with the working shown.Editorial status: source-checked explainer. No independent external technical review is claimed. Spotted an error? See corrections.
