Key Takeaways

- Assessments indicate that there is no consistent understanding of the word “serious” and there is considerable noise in the classification of the same case by multiple people.

- An expert panel used literature from medicine, military, engineering and other disciplines to create the empirical criteria that define a serious injury—the LIFE model.

- A controlled experiment revealed that the LIFE model is reliable, significantly decreases noise, and serves as the foundation for professional collaboration and scientific advancement.


In recent years, the term “serious injury and fatality” (SIF) has become increasingly popular. Companies have created SIF prevention programs, institutes have launched SIF prevention initiatives and the state of California has even established regulatory requirements for reporting potential SIFs (CPUC, 2019). However, despite this momentum, there is no common definition for a serious injury that transcends organizational boundaries. As a result, it is unclear whether people mean the same thing when using the terms “SIF” or “potential SIF.”

Several research organizations, regulatory bodies and institutes have attempted to define a serious injury (NSC, 2020) but, as summarized in Figure 1 (p. 24), there are considerable differences among the approaches. For example, some definitions attempt to explain the word “serious” (known as an intensional definition), while others are based on a list of injury types that are considered serious (known as an extensional definition). In the case of serious injuries, an extensional definition requires creating a comprehensive list of serious injuries that applies across all occupational settings. Extensional definitions are generally less mature and must be updated every time a new incident type is encountered. Alternatively, intensional definitions tend to be preferred because they assign meaning to a concept, phenomenon or occurrence, making them more robust and scientifically useful. As the use of the term “serious” becomes more pervasive, a precise intensional definition is needed that allows people to unambiguously determine what is a serious injury and, perhaps more importantly, what is not serious.

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