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What Are Trailing Indicators?

Occupational safety systems commonly rely on measuring trailing indicators to assess their safety performance. Trailing indicators, also known as lagging indicators, are things like incident numbers, workers’ compensation claims, and past regulatory compliance—in other words, data that answers the question “How did we do?” Although monitoring and measuring trailing indicators is an important part of an organization’s safety system, writer and safety expert James C. Manzella, among others, has asserted that the data resulting from relying on measuring past conditions do not “indicate why a specific level of performance was achieved. Thus, they cannot identify deficiencies that have the potential to produce future injuries or accidents.”1 Measuring trailing indicators alone provides no real evidence of a safety system’s efficacy because it can create the false impression that an absence of incidents necessarily indicates good safety performance.2

But improving a safety system in a way that positively affects present and future safety performance requires using data correctly to understand current conditions and forecast future conditions, and then using that information to eliminate or reduce safety risks. Manzella explains:

To maximize performance and reduce risks, safety and health measurements must focus on conformance to system activities before injury, not on the final outcome of the system (injury performance) – if a safety program relies on after-the-fact data to establish safety performance objectives, those goals will be difficult to reach or maintain.1

What Are Leading Indicators?

Indicators that are anticipatory rather than “after-the-fact” are known as leading indicators. Unlike trailing indicators, which reflect past conditions, leading indicators provide information that can help avoid future problematic or unsafe conditions. They help answer the questions “How are we doing right now?” and “How are we likely to do?” Identifying and measuring leading indicators provides “information while there is still time to intervene and offer a high degree of confidence that intervention is occurring at appropriate points,” according to occupational safety expert R. Scott Stricoff.3 Manzella explains that this intervention can be “incorporated into future plans in order to improve the system, not merely to address the individual incident.”1

Identifying Leading Indicators

Shifting away from over-reliance on trailing indicators and including a focus on identifying and measuring leading indicators could be a difficult process for many business leaders. They may be uncertain about how to go about defining, identifying, and understanding specific available leading indicators within their organizations. If they are not skeptical about the usefulness in identifying leading indicators, they doubt their ability to identify the measurable indicators that can lead to predictive data. But many organizations likely already measure and record information that can expose leading indicators. This includes production statistics, maintenance records, records of employee behavior, and permits for hazardous work. Plus, companies often maintain reports of prior accidents, doctor visits, near misses, and other trailing indicators that can serve as bases for discovering leading ones. Additional sources of leading indicators include demographic information about personnel, like clock-in and clock-out times, and data regarding their usage of equipment, like mechanical diagnostics, location and speed data, and so on. Generally, this data is used only for a single purpose, like for preventative equipment maintenance or the issuing of reprimands or warnings. Safety expert Jack Toellner put it clearly: “Many safety professionals spend a significant amount of time gathering, analyzing and reporting statistics. If these efforts are not directly leading to improved performance, then a site’s safety resources are not being maximized.”4

Further examples of indicators that may suggest predictive trends include data on first-aid cases, near misses, the frequency and scores of safety inspections, employees’ input, management reviews, training completion, and closure of corrective actions, and industrial hygiene samples. There is no universal formula for developing leading measures, but prioritizing safety initiatives that create the biggest impact is key. Incorporating leading measures drives continuous improvement, and continuous improvement drives positive change.

How Predictive Safety Can Help

Predictive Safety’s AlertMeter® and PRISM platforms provide leading indicators in real-time that correlate with worker performance and safety: individual alertness and fatigue level. Even though impairment and fatigue are cited as common contributors to occupational accidents and injuries, a safety system focused on trailing indicators may be oblivious to when workers are dangerously fatigued, ill, on impairing medication, or intoxicated from illicit drugs or alcohol. Worker safety, worker productivity, and workplace culture are directly related, and Predictive Safety can show you how they can be positively affected by incorporating leading indicators into your organization’s safety system.


1. Manzella, J. C. (1999, September). Measuring safety performance to achieve long-term improvement. Professional Safety: 33­‑36.

2. Blair, E. H. & Spurlock, B. S. (2008). Leading measures of safety performance [Conference paper]. ASSE Professional Development Conference and Exhibition. American Society of Safety Engineers.

3. Stricoff, R. S. (2000, January). Identifying prospective indicators with high validity. Professional Safety: 36-39.

4. Toellner, J. (2001, September). Improving safety & health performance: Identifying & measuring leading indicators. Professional Safety: 42-48.